6mm Tac Match cartridge comparisons

[Bugholes]

I have recently decided to build a 6mm Tac match rifle for myself and have done a bit of research to see what was doing well and what viable options are out there. My intention was to build something that was easy to shoot, little/no recoil, and to be used on slightly shorter matches. There are plenty of choices and all the info I seemed to find was one vs another, and info about one, but not a more comprehensive evaluation of overall choices. There may exist something similar to this comparison somewhere, but life keeps me extremely busy and therefore I haven't found the info I was looking for.

SO...

I decided to do what any red-blooded, compulsive, persnickety, American with a lathe and barrels would do- I made one of each.

The Cartridges

The cartridges considered for this evaluation were decided to be mag fed short action chamberings with "reasonable" barrel life and a speed that would be able to compete in many/most matches encountered (I believe the PRS limit is 3150FPS?). Barrel life is a relative term, but I usually find myself changing barrels in 1000-1200 rounds anyway, so I need it to last competitively for that duration. I'm sure many of you will scoff at this, but if I have a barrel thats lost a 1/4 MOA of its accuracy, its coming off! Despite the fact that there are many possibilities, I decided to go with the 6XC (6XC), 6mm Creedmoor (6CM), 243 Winchester (243Win), and the 6-6.5x47 Lapua (6x47L). There are several secondary considerations for all these chamberings that will be reviewed in each subcategory mostly having to do with brass availability, quality, and fire forming requirements. . The test went forward on the premise that all components would be held as equal as possible; all barrels, actions, bullets, powders, will be from the same "lot".

COMPONENTS

The barrels used in this test were provided by Bartlein. All the barrels are spec'd to be cut from the same bar of steel with the same cutter hook, and to the same dimensions (bore/groove). I'm aware that this doesn't exactly create a "level playing field", but it's the closest I could come. The barrel blanks provided were all stainless 29" 8 twist M24s, 5R rifled and finished at 27". Dimensions requested were .2370/.2432, I believe going a little over on the groove size helps the barrel to be more forgiving during load development. All barrels were threaded 5/8-24, have an R&D Mrad brake, and have a contoured and sanded thread protector. A side note, when I discussed the project with Bartlein, they immediately offered to provide the barrels. I have installed many Bartleins but have shot very few, they were extremely generous when they offered to provide these barrels at no charge, and I was very much looking forward to shooting a sample of their barrels. Visual inspection of chamber throats showed similar bore shape indicating that they were indeed cut with the same cutter hook, all barrels took the same bore pilot.


The actions used were Defiance Deviants, all short action repeaters made to the spec that we currently keep in stock. I have used several Deviants, some on my own rifles, but welcomed the opportunity to look at a sample of several actions to evaluate uniformity and accuracy. These actions will come from two seperate batches of actions as I didn't want to set aside 4 actions for the duration of the project. Aside from that, there should be no variables from batch to batch that should affect accuracy and uniformity of these actions so I dont feel this will effect the end results.

The stocks used were AICS 2.0 chassis, primarily because I had two of them on hand. I will note that this is not the most comfortable stock for me, but I couldn't justify the cost of using 4 seperate stocks, bedding etc, to move forward with this. Both chassis were modified by milling out the trigger pocket to accept the Jewell tigger safety linkage; there was no other modifactition or bedding preformed. All action screws were torqued to 65 in-lb


Jewell HVR-TS-A triggers were used for this evaluation, both set at approx 8 oz


Nightforce NXS scopes were used on each rifle, 5.5-22 x50 and 8-32x56. Both scopes always ran on 22 power and both have a proven record as good scopes


LOAD DEVELOPMENT

I have little/no shooting experience with most of these cartridges, and load information was collected from friends, smiths, and the Internet. Generally when I'm working with cartridges that I'm unfamiliar with, I shoot 2 shot groups to move quickly through load development, looking for nodes and pressure limits. Once this is achieved I shoot 3 shot groups to explore nodes, and 5 shot groups to verify loads (when time is available). All testing began at 100 yards; I can shoot suppressed in the back yard safely without bothering the neighbors, therefore all rifles were shot with one suppressor to maintain uniformity. I do not have a reliable resource to shoot year round beyond 100 yards without significant travel, so I explore the areas around the best 100 yard loads at 500-600yds whenever possible. Components were kept as similar as possible to simplify load development and maximize success. A note on chronograph data, I shoot in a pine forest, light can be inconsistent. I use the velocity data as a generalization, often trajectory indicates a higher muzzle velocity than the chronograph indicates. Ive been told I need a "more optimistic" chronograph- so don't pay too much attention to ES numbers, etc

These will be sold when I can get a for sale post together, I will link the sale thread here soon

there will be a lot of info here, so Im going to break up the thread in multiple posts as I go along, please be patient. In addition, posts will be edited as I insert missed/forgotten info, etc

 

[Bugholes]

6MM XC

The 6XC was the first up, I have heard many shooters have had high success with this cartridge, so I thought it would be a good place to start. My XC reamer has .273 neck and .130 freebore, the reamer cut great and there was no problems with the barrel install. I bought 500 pieces of brass from Tubb, cost was $.88 without shipping, loaded rounds were .270" at the neck. I waited several months for this brass to come in, I believe this is a single source supplier. The primer pockets needed significant cutting with a squaring tool, the flash holes required no work. I used Berger 105 Hybrid and Sierra 107 match king, and H4350 powder only

Regarding bullet seating depths, both bullets were jumped approx. .020", the overall length of the cartridges loaded with 105s and 107s fit with ease in an standard AICS magazine. I do not do the shoot/clean/shoot/clean break in, I usually just get shooting and clean when I switch bullets or powders. The first targets are on the small boxes all shot at 100 yards, the targets with the orange dots were shot at 570 yards at Manatee Gun Club in Bradenton, FL. Manatee is a difficult range as the winds are switchy and the mirage here in south Florida in the summer/fall is heavy and troublesome. The two small groups fired from the XC were both shot (consecutively) over a 3 minute period where the entire range was covered with clouds and the wind stopped. This shows how much the conditions can make a good gun into an average gun or vice versa. Many other targets shot with the XC were in the 2-3" range.

The XC was a breeze to load for, I think you could go to a match with just about any load tested here and be competitive. The functional performance zone of the XC seemed to be 2950-3030, there are lower nodes but why bother? I'll go with accuracy and performance if I can. I was able to get up over 3100fps but the accuracy was starting to fall off and I was starting to get ejector prints. There was a total of about 120 rounds fired during this test, the primer pockets are nice and tight throughout the test.

 

[Bugholes]

6MM Creedmoor
I did the 6CM along with the XC, load testing was done at a similar time of year in similar conditions. My 6CM reamer has .275 neck and .123 Freebore. As I understand it, others may be using a freebore of closer to .200", I spec'd the freebore to be used with 105s, the bullet seating layout looks good in a loaded case when the bullet is loaded at the lands. The brass was Hornady brass headstamped 6mm Creedmoor, bought from GA precision for $.65 each without shipping, loaded rounds measured .272" across the neck. I used Redding type S bushing full length 6.5mm Creedmoor sizing die with a 6mm bushing, and a whidden competition 6mm Creedmoor seater die ordered directly from Whidden.

I was impressed with the Hornady brass, I ran it through the sizing die and there was no sizing performed. Necks were round, primer pockets required little/no cutting, but all the flash holes were cleaned as there was a visual burr in many cases. I believe GA is the primary/sole source of this brass, others may sell it but it all originates from GA Precision, I believe. The brass was available when I called, apparently GA buys LARGE lots of this brass and it is available most of the time.

Seating depths were .020" off again, these cartridges would fit nicely into an AICS mag without magazine modification. They ran properly from both AICS and AIAW mags. The 6CM was easy to load for, the nodes were a little more pronounced than the XC. Its apparent that you can get about 2 more grains of powder in this case yielding 80-150 fps of velocity benefit over the XC. The functional velocity range of the cartridge was 3000-3150, better performance that's closer to speed limits set on many matches. There were, of course, lower nodes

small box targets were shot at 100 yards, large orange circles were shot at 570 yards at Manatee Gun Club the same day as the XC from above. There was approximately 135 rounds fired in this test, the primer pockets are noticeably loose after 3 firings
Load density with H4350 was less than 100% even with a 44 grain charge (my max). If a longer freebore was used I would be interested in exploring magnum powders and possibly a 115 grain bullet. The case has the power to pull it off and would have extra case capacity for a slower burning powder if the bullet was seated further out. In general, these groups were a little larger on average than the XC, but there is a noticeable speed benefit. I did not get the opportunity to shoot in ideal mirage conditions with the CM, but if it will produce 2-2.5" groups on the 570 yard line, it meets my accuracy standard (especially with me shooting...). FYI the smallest group the CM produced was .866" at 570yds, but I could not duplicate this

 

[Bugholes]

6x47 Lapua
The 6x47L and 243Win were done approx. 8 weeks after the XC and CM, temperatures were a little cooler and I now have a thermal shield for the suppressor for 100 yard groups. Some of the groups from the XC and CM were less than ideal trying to shoot through suppressor mirage in 90 degree temperatures, took a little while but I finally got a cover to control the heat.

The 6x47L reamer used had a .273 neck and .104 freebore, loaded rounds measured .269" at the neck. Brass used was from Lapua, of course. Cost was $1.05 per piece, primer pockets took a light cutting, flash holes did not need to be deburred. The quality of the Lapua brass was evident, necks were round and ding-free, I did not run them through a sizing die- Just load and shoot. Visual inspection of the case shows that its a little shorter than the XC but with similar neck length and body taper, this was the lowest capacity cartridge of the 4 tested

Brass needed to be formed from 6.5x47 brass. I tried the recommended method of running the new brass through a bushing die and sizing all in one step, necks were lubed with Redding Imperial sizing wax. All in all, I found this quite frustrating as many/most of the shoulders collapsed in this one-step process. I also had a forester full length sizing die in 6X47L, this too caused neck/shoulder collapse. Eventually after trashing 15 or so cases at $1 each, I moved to an intermediate bushing to size down the necks in 2 steps, full forming by dies was complete in 3 sizing steps. First the lubed cases were sized with a .280 bushing, then run through a .269 bushing. The bushing leaves a radius on the neck/shoulder junction that I thought might be trouble, so I ran it through the forester 6x47 full length die to get a resizing of the entire neck. Brass was nicely formed but it took time. Redding type S bushing full length dies were used for resizing purposes once the brass was fired. The brass has small primer pockets, CCI BR-4 primers were used here while BR-2 primers were used in all other cartridges. Obviously this brass is available in many retail stores, but Lapua is the only option. Im not aware of any way to make this brass if it becomes unavailable on the retail market

The cartridges were plenty short enough to run through AICS mags when bullets were loaded at the lands, this was the shortest cartridge overall because of case length and freebore dimensions. More freebore could be a benefit as the neck is rather long and you could free up more capacity without causing an overall length concern. Again I was looking to shoot 105s only and the reamer came with the above freebore. Dimensionally it looks correct (as far as bullet seating depths)

I started testing with H4350 as it seems to be popular with most shooters, functional accuracy seemed to be in the 2900-3000fps range. Since the load density was nearing 100% at 41 grains, I wanted to try a faster powder to see if more speed was possible. I used IMR4064 since it has a higher load density than Varget or RL-15, still trying to keep the case almost full if possible. The speeds from 4064 did open up a faster node; the accuracy at 100 yards was acceptable but the accuracy at 300 yards was not. Varget would be an appropriate substitute if one was to keep looking for powder options, I was trying to get solid info from 3 firings of the brass- didn't need to put hundreds of rounds through in search of the perfect load.

Small box targets were fired at 100 yards, multiple targets on single cardboard piece were fired at 300 yards with IMR4064 and both 105 hybrid and 107 SMK. individually cut out cardboard squares were fired at 500 yards with H4350 and the 105 Hybrid only. The 300 and 500 yard groups were fired at a private range with the land owner, we were able to start early before the wind and mirage got too bad. When conditions started to deteriorate, we moved to the 300 yard line, winds were light and blowing between 2-7mph full value. Both the 6x47L and the 243 Win were shot at the same times in the same conditions, 500 yards is the max distance available at this property.

there were a total of 110 rounds fired during this test, the primer pockets remained tight throughout the reloading process. I cant imagine a slower burning powder (than H4350) being very beneficial in this case, in fact I would consider looking at a faster powder to try and uncover a little more speed. All in all the accuracy nodes were quite large, it would be easy to find an acceptable load with this cartridge. Reviewing the 500 yard targets showed good accuracy at this distance, but I cant help to wonder how it would be to shoot this thing on a calm day- vertical dispersion in these groups was average, accuracy was acceptable. Groups were a little better than the creedmoor (comparatively, different distances) and on par with the XC

 

[Bugholes]

243 Win
the 243 Win testing was done at a little cooler time of the year as mentioned above, 85 degree weather instead of 90+ degrees. The 243Win reamer I used has a .275 neck and .060 freebore, the lead angle is 3/4 degree rather than 1 degree-30, this causes the throat to be "longer" since the angle is more gentle. The loaded brass measured .271" across the neck.

Lapua brass was used exclusively for this test; the brass needed little work, a light cut on the primer pocket and no flash hole deburring. I did not size the brass before shooting, necks were round and bullets seated nicely with consistent neck tension. 243 Win brass is available from a number of manufacturers so that's a big plus for 243 shooters. Redding type S bushing full length sizing dies were used, I usually select a bushing that provides .001 or .0015 neck tension if possible. Overall length of these cartridges were short enough to fit in a BDL box and there was ample room to run inside a standard AICS magazine. The boat tails were noticeably seated into the case body occupying potential powder space. The 243Win has the shortest neck of all cartridges tested, largest powder capacity, and is the longest overall. I decided to leave the cartridge at this length to be a little more "fair" with the others in the evaluation. Eventually I pushed the throat forward to free up some powder capacity, more on this in a minute

Bullets tested were 105 Hybrid and 107 SMK, all bullets were loaded to .020 off the lands. I started with H4350 since I had used it in all the other cartridges, but eventually went to magnum powder later on in the test. I have owned and shot several barrels in 243AI, and the magnum powders usually are chosen to achieve max velocity with heavy bullets, the case capacity with the first throat was not enough to run large charges of magnum powder without having compressed loads. First targets were shot with H4350 on the original throat, accuracy was not what I wanted out of my rifles, functional speed was 3000-3120. The rifle felt fussy and didn't want to consistently group at 100 yards, I had trouble getting reliable chronograph data, so the target progression seems like I'm jumping all over the place looking for info. First reload the velocities went up with H4350, but accuracy continued to be erratic. I pulled the barrel off and pushed the throat forward

The new throat was set up around the two test bullets loaded to clear the deviant magwell and run inside a modified AICS mag, this allowed room to run in an AW mag as well, but not a standard AICS. The new throat opened up some powder capacity and I switched to IMR7828SSC and resumed the testing. 7828SSC has a burn rate similar to H4831SC and RL22, but it has lower load density and Quickload predicts lower pressures and higher velocities. I shoot 7828 in many cartridges, and I can agree with the QL prediction. The groups started becoming a little more predictable, and I feel like this was a good direction to go to get the last bit of performance out of this thing. Unfortunately I wasn't able to get complete chronograph data for the 7828 loads, but Im expecting this brought the functional velocity up to 3025-3175.

The accuracy at 500 yards was a bit of a surprise considering how things were looking at 100 yards, but I was pleased with the results. I would estimate these charges were getting 3100-3150fps, this speed with this accuracy would be an effective match offering. There is the potential to comfortably run 115s in the 243, I didn't explore this but have interest to see if it would offer a ballistic advantage to the 105s. This could help getting all hit points at 900 yards and beyond, Ive seen guys make hits with 105s going slower and they are hard to distinguish at long range due to the decreased energy delivered on target. There was 90 rounds fired through the barrel, primer pockets were acceptably tight considering some of the loads used were pretty stout

 

[Bugholes]

Conclusions
at this point, there is a better understanding about the benefits and capabilities of these cartridges, what appeals to me may not appeal to others. My considerations for a good match cartridge include:
-short range accuracy. (tiny dot stages at 50 and 100 yards)
-long range accuracy. (know your limits and hostage stages)
-velocity. speed equals less wind drift and flatter trajectories. (UKD stages, windy matches)
-tuneability. theres no place for a great load with small nodes. barrel temps, regional temps can throw off a small node
-brass. I don't want to form or prep brass if I don't have to, theres always pieces left behind at matches.

6XC- easy, accurate, ready to go. Not the fastest, but the short and long range accuracy is there and the nodes were huge. The cartridge was very easy to tune, brass is available with a little bit of pre-planning. Brass can be formed from 22-250 if necessary, but I can tell you I wont be doing that. Both bullets used shot well, the 105 Hybrid showed an advantage at longer distances. Im torn between the 6XC and the 6CM as my first choice. the XC seems to have an accuracy advantage so Im leaning a little this way

6 Creedmoor-a little more effort in load development, but the short range accuracy was outstanding and the long range accuracy was very good. Getting the extra speed over the XC is an attraction, as is the reasonably priced and available brass. I don't know if I was running my loads too hot or not, but the primer pockets seemed to be blown out prematurely. My velocities were on par with others who shoot the CM despite I was using larger powder charges (this can be said for the other 3 tested as well). Id really like to see what the CM would do in good conditions, Im not sure I saw the complete accuracy potential because of range conditions on my long range days. Also attractive is the available power to push the 115s to a competitive speed. This should be considered with a longer throat and magnum powders

243 Winchester- The 243 surprised me with its accuracy on the 500 yard line. This with the velocity and power available offers the highest level of performance in the wind and in UKD stages. I was a little disappointed with the short range accuracy, and found the barrel to be a little fussy as mentioned earlier. but theres no denying that .25MOA long range accuracy with maximum speed is a game changer. The power to push the 115s is a realistic attraction to many as well. All in all I think that I had a little less confidence in the 243 than the XC and CM. Also after throating the chamber for longer OAL, a magazine constraint was introduced- either be set up for AW mags or find a guy with an EDM and have him burn off the forward plates in your AICS mags

6x47 Lapua- I don't see the attraction of this chambering in a tactical match rifle, it did not excel in any part of this evaluation (except the possibility of extended brass life). I found the brass forming to be frustrating and the cost of the brass was the highest of all samples. If Im going to form brass and spend top dollar on it, Id prefer to not leave it in the grass. I can see this as a varmint or benchrest cartridge, or for an application where loosing brass is less likely. Several guys shooting this have told me they get a very high number of reloads on the brass. Accuracy at 100 was good, accuracy at 500 was good, but it was the slowest cartridge tested- not by much, but my loads seemed to be best in the 2970-3000 range. I don't see what the x47 can do that the XC cant do

 

[steve123]

This will be a fun post!

Are you going to pick a standard OACL based off the ogive of one particular bullet for all the cartridges and have them throated the same?

 

[Bluejazz]

Tag for future reference

 

[223Rem]

This should be interesting.

Big fan of the .243 Winchester.

 

[Nrdon]

Tag.

 

[Rustybroadhead]

tag

 

[Grumpy61]

tag as well

 

[BERTMAN77MK2]

Awesome post! Can't wait for final results---thank goodness you are in the barrel business!!

 

[Pusher591]

Tag in

 

[bjay]

tag to read later

 

[tigerfan_9]

FYI...you don't have to post a tag, just go to thread tools and hit subscribe.

 

[TRAAV]

Yep looking forward to seeing what you come up with.

 

[65guys_steve]

Following with interest....


Sent from my iPad using Tapatalk

 

[McLarenross]

Nice! Im looking forward to the conclusion of this very much.

 

[Marksman]

Oh yeah, tagging this for later.

 

[mckenzie]

making us wait ,its like waiting for x-mass

 

[leadbullet]

Thanx bugholes, everything I wanted to know about the 6 creedmoor is covered.
Looking forward of the rest and conclusion

 

[bjay]

wow creedmoor is laser!! i like what im seeing on 42.5-43.5....

 

[peaceatwar]

So far so good. Hopefully your conclusions will help some people make their decisions.

 

[Graham]

Interesting test. Thanks for that.

 

[Disturbed]

Tag. Looking forward to more results.

 

[kvwpwr]

Excellent info! Any chance you are going to manatee tomorrow?

 

[yetigoode2]

Looking forward to the 243 win you're building for me. Great info.

 

[kvwpwr]

I may have overlooked it but what twist barrel did you use?

 

[bjay]

Im interested to know a little info about 6mm creed that were used...tnx

 

[Frank Green]

6x47 Lapua
The 6x47L and 243Win were done approx. 8 weeks after the XC and CM, temperatures were a little cooler and I now have a thermal shield for the suppressor for 100 yard groups. Some of the groups from the XC and CM were less than ideal trying to shoot through suppressor mirage in 90 degree temperatures, took a little while but I finally got a cover to control the heat.

The 6x47L reamer used had a .273 neck and .104 freebore, loaded rounds measured .269" at the neck. Brass used was from Lapua, of course. Cost was $1.05 per piece, primer pockets took a light cutting, flash holes did not need to be deburred. The quality of the Lapua brass was evident, necks were round and ding-free, I did not run them through a sizing die- Just load and shoot. Visual inspection of the case shows that its a little shorter than the XC but with similar neck length and body taper, this was the lowest capacity cartridge of the 4 tested

Brass needed to be formed from 6.5x47 brass. I tried the recommended method of running the new brass through a bushing die and sizing all in one step, necks were lubed with Redding Imperial sizing wax. All in all, I found this quite frustrating as many/most of the shoulders collapsed in this one-step process. I also had a forester full length sizing die in 6X47L, this too caused neck/shoulder collapse. Eventually after trashing 15 or so cases at $1 each, I moved to an intermediate bushing to size down the necks in 2 steps, full forming by dies was complete in 3 sizing steps. First the lubed cases were sized with a .280 bushing, then run through a .269 bushing. The bushing leaves a radius on the neck/shoulder junction that I thought might be trouble, so I ran it through the forester 6x47 full length die to get a resizing of the entire neck. Brass was nicely formed but it took time. Redding type S bushing full length dies were used for resizing purposes once the brass was fired. The brass has small primer pockets, CCI BR-4 primers were used here while BR-2 primers were used in all other cartridges. Obviously this brass is available in many retail stores, but Lapua is the only option. Im not aware of any way to make this brass if it becomes unavailable on the retail market

The cartridges were plenty short enough to run through AICS mags when bullets were loaded at the lands, this was the shortest cartridge overall because of case length and freebore dimensions. More freebore could be a benefit as the neck is rather long and you could free up more capacity without causing an overall length concern. Again I was looking to shoot 105s only and the reamer came with the above freebore. Dimensionally it looks correct (as far as bullet seating depths)

I started testing with H4350 as it seems to be popular with most shooters, functional accuracy seemed to be in the 2900-3000fps range. Since the load density was nearing 100% at 41 grains, I wanted to try a faster powder to see if more speed was possible. I used IMR4064 since it has a higher load density than Varget or RL-15, still trying to keep the case almost full if possible. The speeds from 4064 did open up a faster node; the accuracy at 100 yards was acceptable but the accuracy at 300 yards was not. Varget would be an appropriate substitute if one was to keep looking for powder options, I was trying to get solid info from 3 firings of the brass- didn't need to put hundreds of rounds through in search of the perfect load.

Small box targets were fired at 100 yards, multiple targets on single cardboard piece were fired at 300 yards with IMR4064 and both 105 hybrid and 107 SMK. individually cut out cardboard squares were fired at 500 yards with H4350 and the 105 Hybrid only. The 300 and 500 yard groups were fired at a private range with the land owner, we were able to start early before the wind and mirage got too bad. When conditions started to deteriorate, we moved to the 300 yard line, winds were light and blowing between 2-7mph full value. Both the 6x47L and the 243 Win were shot at the same times in the same conditions, 500 yards is the max distance available at this property.

there were a total of 110 rounds fired during this test, the primer pockets remained tight throughout the reloading process. I cant imagine a slower burning powder (than H4350) being very beneficial in this case, in fact I would consider looking at a faster powder to try and uncover a little more speed. All in all the accuracy nodes were quite large, it would be easy to find an acceptable load with this cartridge. Reviewing the 500 yard targets showed good accuracy at this distance, but I cant help to wonder how it would be to shoot this thing on a calm day- vertical dispersion in these groups was average, accuracy was acceptable. Groups were a little better than the creedmoor (comparatively, different distances) and on par with the XC

Greg, My reamer has a .273" nk. As you said you have to neck down the 6.5 Brass. I used the Redding comp. dies. I took the seater stem out of the seating die and ran the brass into this set up first. It necks the case down approx. half way. Around .280" diameter or so. Then I ran my brass thru the sizing die with my neck bushing in it. Never lost a piece of brass.

Later, Frank
Bartlein Barrels

 

[Bugholes]

Excellent info! Any chance you are going to manatee tomorrow?

no sir, Ive got too many barrels to put on. Id prefer to wait till it cools down a bit

This will be a fun post!

Are you going to pick a standard OACL based off the ogive of one particular bullet for all the cartridges and have them throated the same?

I make a chambering aid with every barrel install, this helps determine distance to the lands with any bullet. Jump/jam is determined from this info

I may have overlooked it but what twist barrel did you use?

All barrels are 8 twist, Ive modified the first post to reflect this info

 

[steve123]

This will be a fun post!

Are you going to pick a standard OACL based off the ogive of one particular bullet for all the cartridges and have them throated the same?

Haha, you were still posting while I was asking, so my questions are answered.

I'm surprised you had so many problems necking down to 6mm in the 6x47. Although it's been 6 years since I've necked down for mine I don't remember any cases getting buckled. I did use a custom FL die though instead of a bushing die. I think back then I used Hornady OneShot lube and sprayed a plastic bag full of cases. Maybe that helps in the necking down process???

For my second batch of 500 brass I set a false shoulder and left the OneShot on which seemed to improve accuracy when fireforming.

One last thing, my reamer is cut as close as possible to the virgin brass but with a .270 neck and extra long freebore of .208" for the 115's. With the reamer set up this way I ended up using H-4831 as the powder of choice. 115's at just over 3000 fps in 26" barrels were where the high node was. On the newest barrel which is 30" I'm running 105HB's at 3140 fps with 43.1 grains, which is warm load but not a hot load. I've got maybe 15 firings on the brass and the pockets are still tight.

Thanks for posting this interesting test!

 

[bward]

Very interesting results. I too have played with all of the above cartridges and found the accuracy capability and velocity capability of each to be nearly identical to your findings.

 

[glockaholic]

I think there is something missing from the Conclusions post..... :-0

 

[varmint slayer]

I think there is something missing from the Conclusions post..... :-0

It's merely a place holder for when he gets the conclusion done. It's so all his data is in a row and not spread out all over the thread.

 

[bustin]

6MM Creedmoor
I did the 6CM along with the XC, load testing was done at a similar time of year in similar conditions. My 6CM reamer has .275 neck and .123 Freebore. As I understand it, others may be using a freebore of closer to .200", I spec'd the freebore to be used with 105s, the bullet seating layout looks good in a loaded case when the bullet is loaded at the lands. The brass was Hornady brass headstamped 6mm Creedmoor, bought from GA precision for $.65 each without shipping, loaded rounds measured .272" across the neck. I used Redding type S bushing full length 6.5mm Creedmoor sizing die with a 6mm bushing, and a whidden competition 6mm Creedmoor seater die ordered directly from Whidden.

I was impressed with the Hornady brass, I ran it through the sizing die and there was no sizing performed. Necks were round, primer pockets required little/no cutting, but all the flash holes were cleaned as there was a visual burr in many cases. I believe GA is the primary/sole source of this brass, others may sell it but it all originates from GA Precision, I believe. The brass was available when I called, apparently GA buys LARGE lots of this brass and it is available most of the time.

Seating depths were .020" off again, these cartridges would fit nicely into an AICS mag without magazine modification. They ran properly from both AICS and AIAW mags. The 6CM was easy to load for, the nodes were a little more pronounced than the XC. Its apparent that you can get about 2 more grains of powder in this case yielding 80-150 fps of velocity benefit over the XC. The functional velocity range of the cartridge was 3000-3150, better performance that's closer to speed limits set on many matches. There were, of course, lower nodes

small box targets were shot at 100 yards, large orange circles were shot at 570 yards at Manatee Gun Club the same day as the XC from above. There was approximately 135 rounds fired in this test, the primer pockets are noticeably loose after 3 firings
Load density with H4350 was less than 100% even with a 44 grain charge (my max). If a longer freebore was used I would be interested in exploring magnum powders and possibly a 115 grain bullet. The case has the power to pull it off and would have extra case capacity for a slower burning powder if the bullet was seated further out. In general, these groups were a little larger on average than the XC, but there is a noticeable speed benefit. I did not get the opportunity to shoot in ideal mirage conditions with the CM, but if it will produce 2-2.5" groups on the 570 yard line, it meets my accuracy standard (especially with me shooting...). FYI the smallest group the CM produced was .866" at 570yds, but I could not duplicate this

Similar to what I saw in the 6mm Creedmoor(not to be confused with the 6CM). The primer pockets do not hold up well, Win or Lapua 308/260/243 brass formed holds up much better. Try the 6CM or 243-30degree AI more or less, there's more room to find nodes within the velocity range needed.

 

[glockaholic]

It looked like the accuracy order is 6x47L, 6XC, 6CM, and 243 last. That's based on the 500yd groups but then some were 570 yds. It's great to see this write up. I'm interested in more information on the 6mm. I've been shooting a 6SLR lately and watching the velocities for nodes.

 

[Bugholes]

left to right: 6X47 Lapua, 6XC, 6MM Creedmoor, 243 Win. All loaded to the OAL used in this evaluation with Berger 105 Hybrids

 

[Steelhead]

It looked like the accuracy order is 6x47L, 6XC, 6CM, and 243 last. That's based on the 500yd groups but then some were 570 yds. It's great to see this write up. I'm interested in more information on the 6mm. I've been shooting a 6SLR lately and watching the velocities for nodes.

From what I'm seeing the .243 actually took top spot accuracty wise:

243 = 2.385", 1.28", 1.49" for an average of 1.718" at 500 yards

6x47 = 2.56", 2.165", 1.77" for an average of 2.165" at 500 yards

6 Creed = 2.16", 2.15", 2.48", 2.91" for an average of 2.425" at 570 yards

6XC = 2.4", 2.729", 1.051", 1.253" for and average of 1.858" at 570 yards

There's 1/2" difference between groups at both ranges and the OP stated that conditions weren't ideal, other than when he shot the .243, when there was hardly any wind at the time.

To me the data sampling, while good, is still too small to determine much, other than they are all very similar. It would be interesting to see what happens at 1000 yards with each cartridge, after the best accuracy node is found.

 

[jakelly]

This is great thanks. Makes the advantages of the 6SLR sound interesting.

 

[SquarePizza]

Impressive, thank you for your post.

Also, you came up in conversation just the other day when I was on the phone with Jerome Soltis about 6mm rifles, small world that I would see your post a day later. =P

 

[mcfred]

Great thread! Thank you for sharing your results here.

 

[6brshooter]

Maybe i have been lucky but on my 4 243 win load work ups were a breeze. Actually had a 6 br f class rifle that was finickier then my 243. I have a LW,Brux,Krieger, and Criterion barreled 243, all 8 twist 105 h-vld, 107 smk, and 105 hybrids have all worked good at 20 thou off. Not sure of reamer specs though. I find [email protected] will get me to 3100-3175 in 24&25.5" barrels. In the longer tubes( older builds) i use h4831sc. They aren't hot loads, around 3050, but just bughole. When h4350 got tight i experimented with h4831sc in my 24" criterion remage. 43.5 gave me 2980 and 3 shot groups in the 0s and 44.5 got me 3040 and several5 shot groups in the .1s, all from a bipod and prone. I do know loaded rds set 20-30 thou off have very little bearing surface below the nk/shoulder junction and fit in aics mags gtg. Excellent write up and great info Greg.

 

[KaiserNorton]

Greg, My reamer has a .273" nk. As you said you have to neck down the 6.5 Brass. I used the Redding comp. dies. I took the seater stem out of the seating die and ran the brass into this set up first. It necks the case down approx. half way. Around .280" diameter or so. Then I ran my brass thru the sizing die with my neck bushing in it. Never lost a piece of brass.

Later, Frank
Bartlein Barrels

I size my brass via the 6x47 Forster full length die, using a copious amounts of lube (interior and exterior) and never lost a case in the process.

The Kaiser

 

[NDVarmint]

Following this, interesting...

 

[SScott]

6mm

Thanks for your work on this, the 6mm's interest me, but the short barrel life is what scares me away.
Scott

 

[Niles Coyote]

Awesome Greg, I'll be watching with interest.

 

[turbo54]

Thanks for your work on this, the 6mm's interest me, but the short barrel life is what scares me away.
Scott

Understandable. It comes down to intended usage. The 6s excel in PRS type rifle matches where finishing order is often affected by even 1/2 point. Its low recoil is ideal for fast-paces stages. Obviously, the high velocity is helpful for trajectory and windage.

However, increase the range past 1000 and the 6s lack impact energy, and are outmatched by some of the slower speed, higher BC choices.

The 6s are not advantageous for casual range time, where the shorter barrel life really sucks.

However, for match usage, consider the costs of entering matches, time off work, fuel, lodging, food, ammo etc etc, and the extra ~$20 in barrel consumed per match by the 6 is kind of just a drop in the bucket. If the bbl lasts 1500 shots - that's quite a bit of match shooting.

Not trying to "sell" you on a 6, just tossing out some talking/thinking points.
[MENTION=16989]Bugholes[/MENTION] Nice test, thanks for posting.

 

[Bronco]

I've been told I'm a 6mm whore, 6 Dasher, 6XC, 6X47L, 243, 6 RAT, makes buying bullets in quantity easier. The 243 was the hardest for me to get shooting well, took around 200 rounds to find a load. The one I ended up with is a good one (42.5 gr 4831sc with a 105 Berger Hibred). 6 Dasher is by far my favorite, most accurate, least recoil, easiest load development. Brass lasts a long time (15 loadings) as does the barrel, got around 2000 rounds on current setup and it shoots sub 1/2 moa groups. Expect to get 3 to 4000 rounds before accuracy fades. Load is 33 gr. of 8208 XBR with the 105 Berger going 2970 out of a 24" barrel. 6's can be competitive and last a long time.