308win Bartlein 5R vs Krieger 4 Groove Accuracy Testing

I am definitely in the less is best group when it comes to cleaning.

Ill be cleaning as follows on both barrels:
After 100rds, Ill make 4-5 strokes with a wet nylon brush then dry patch it out. I then shoot 10 fouling rounds before shooting my OCW. Ill then do all my load development and seating depth testing. Thats about it
[/QUOTE

sounds good..100 is a good range day or 2.
nice medium between Benchrest cleaning and the “nevers”
 
Do you typically load the new lapua cases right out of the box or do you use anything on the necks first? Thank you

As stated above, I just wanted to get rounds down the barrel so I just loaded them.

If I'm loading a known load into new brass for a barrel I'm currently shooting then yes, I'll run the new brass over my 21st Century TiN mandrel
 
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I just want to clear a few things up based on some comments, etc. This test is to see if there is any measurable, noticeable difference between a 308win Bartlein 5R or Krieger 4 Groove for the average shooter, shooting the way 99% of the people on THIS forum shoot. Not benchrest, not in a mechanical rest/test fixture, etc. I hope that clears up some of the questions, or complaints about this test and how its being performed.

While some may be interested in the results of a true barrel only accuracy test in a test fixture, most of the members wouldn't because they will never be out there shooting in a test fixture. I think seeing the results of this test will be much more pertinent to the masses as its how most everyone willbe shooting one of these barrels.

As a forum member (not the person running the test) my guess right up front is that there will be no measurable difference in accuracy for 99% of the shooters out there. Thats just my opinion, I also look forward to the final results. The one unknown for me is the factory ammo test. Its been 10+ years since I shot factory ammo, especially FGMM 308 so thats the only unknown I have on how it will shoot in both barrels. I have zero doubt that I will be able to work up an equally accurate load in both barrels. Will it be the same load for both, idk but I dont think it will be far off if its not.

I have an offer from a supporting vendor to discuss a mechanical test fixture for this test (and could be used on future barrel tests). The test will be run as stated above. If a mechanical test fixture comes to reality, then I may shoot the final loads and some factory ammo out of it at the end of the test. We will see

Now back to your regularly scheduled program
 
OK I'll jump in here and make a few comments.

One is guys as Dominic has pointed out...his sample size is one barrel each.

In my opinion if you want to run a accuracy type test you would do 10 barrels each. All done with the same chamber reamer, and all of the barrels out of the same lot of steel even though from two different makers and use the type and lots of ammo. Same cleaning procedures, rate of fire, same shooting conditions etc...take as many variables out of the equation as possible.

I look back at when GAP had to build like 200 new FBI guns. We made all the barrels and all of them where in 308win. George shipped the first 40 guns just prior to shot show one year. He had to test fire all of the rifles prior to shipping them. He was so impressed with the accuracy that he made a bulletin board with the rifles s/n and the test target. Those first guns he shipped averaged like a .190" for group size. Worst gun was like a high .3xx" or so.

I'll also throw this in there as well. We make a ton and I mean a ton of ammunition test barrels. Both pressure and accuracy barrels and yes you can use the pressure barrels for accuracy as well.

All of the data I've gotten back from ammo makers, bullet makers etc...where they have tested 5R rifling, 4 groove, 6 groove etc...as well as standard 5 groove barrels they for the most part can tell no difference in accuracy.

This what I tell guys. "The straighter the blank, the more stress free it is, the more uniform the bore and groove sizes are over the length of the barrel and the more uniform the twist rate...the more forgiving the barrel is going to be."

Later, Frank
Bartlein Barrels
 
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I'll also throw this in there as well. We make a ton and I mean a ton of ammunition test barrels. Both pressure and accuracy barrels and yes you can use the pressure barrels for accuracy as well.

All of the data I've gotten back from ammo makers, bullet makers etc...where they have tested 5R rifling, 4 groove, 6 groove etc...as well as standard 5 groove barrels they for the most part can tell no difference in accuracy.


To go back to the above....this has been in calibers like 6.5CM, 300WM, 300PRC, 300 Norma, 338 Lapua, 223, pick your poison on 6mm's and 6.5's, 7mm's (just to name a few) etc...no real difference can be found per say.

The only exception to this rule I make is this. If you are shooting a 6PPC benchrest gun and the short jacket 66gr to 68gr type bullets. They do not like the 5R rifling. I tell guys the best you will get out of it is upper .2xx's to flat .3xx's. Why? Those bullets have a real short bearing surface and it's worse with a boat tail bullet. The rifling does the driving of the bullet and they don't like the 5R. Now stay with standard rifling and I don't care if it's standard 5 groove, 4 groove, 6 groove and we've even made 8 groove and 3 groove barrels and they will shoot in the .1xx's.

Now take a 6mm and run heavy bullets like 107's etc...no difference in terms of accuracy and the number or style of grooves. All my 6mm heavy bullet guns have 5R rifling.
 
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I do say also that the 5R rifling does help fight bullet failure. More of a problem in calibers like 224, 6mm, 6.5mm etc...not as much in a 30cal.

Also late last year thru radar testing it helped the flight of the bullet in the transonic range. A 5R and a 4 groove barrel where both tested and every time the test was done the 4 groove always had a hiccup but the 5R didn't. Now this is minimal in my opinion but your talking about a set range like 700 or 800 yards down range in a caliber like 6.5CM etc...but once past that transition area the 4 groove bullet/barrel settled back down from what I remember on seeing the data.

Something else is on my mind but cannot remember....I'll be back when it comes to me.
 
I do say also that the 5R rifling does help fight bullet failure. More of a problem in calibers like 224, 6mm, 6.5mm etc...not as much in a 30cal.

Also late last year thru radar testing it helped the flight of the bullet in the transonic range. A 5R and a 4 groove barrel where both tested and every time the test was done the 4 groove always had a hiccup but the 5R didn't. Now this is minimal in my opinion but your talking about a set range like 700 or 800 yards down range in a caliber like 6.5CM etc...but once past that transition area the 4 groove bullet/barrel settled back down from what I remember on seeing the data.

The differences must be *very* small and transition stability may possibly as simple as just being bullet related (as you point out with the short benchrest bullets vs number of grooves at 100 yd). Lots of F tr / palma guys shooting 600-1000, most certainly getting into the "transition" zone at 1k, and still holding very very small water lines (very little stability issues) with 4g barrels, and plenty of match wins / national records in every discipline with 4G as well.
 
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The differences must be *very* small and transition stability may possibly as simple as just being bullet related (as you point out with the short benchrest bullets vs number of grooves at 100 yd). Lots of F tr / palma guys shooting 600-1000, most certainly getting into the "transition" zone at 1k, and still holding very very small water lines (very little stability issues) with 4g barrels, and plenty of match wins / national records in every discipline with 4G as well.

I'd agree with that!

More guys run 5r rifling in FTR and F Class than what you might think. All of the Team Berger guys are running 5R rifling for example and when those old timers show up at a match...expect to get a whooping! LOL!

The saami spec. for 30-06 and 308win is still 4 groove as are a few other calibers. 4 groove isn't going to go away etc...
 
I'd agree with that!

More guys run 5r rifling in FTR and F Class than what you might think. All of the Team Berger guys are running 5R rifling for example and when those old timers show up at a match...expect to get a whooping! LOL!

The saami spec. for 30-06 and 308win is still 4 groove as are a few other calibers. 4 groove isn't going to go away etc...

Thanks for your input Frank
 
Why not a 5R from Krieger. Both barrels the same?

Because if you read my OP you would know why. This came about because of a back and forth about some camps stating a Krieger 4 groove was more accurate in 308 than a Bartlein 5R. Some stating the Bartlein 5R was more accurate, some stating they were equally accurate. Some stating they wont even chamber Bartlein 5R's, and would only chamber Krieger 4 grooves, vice versa, etc. etc. etc.

You can go back and read that thread if that interests you but that is the basis of this comparison/testing.


And I want to say that this testing and comparison will be about real world raw data. We wont be using single groups, or smallest groups to determine if one is more accurate than the other. Averages is what I like to use. So in the end, best worked up load for both, and factory ammo for both will be agg across 5 or 6 groups of 5 @ 100yds. That number is what I will use as my final accuracy basis for each barrel.

We all know you can shoot 1 five shot group that is one hole, etc. but Ive yet to see anyone do it 5x or 6x in a row. Thats how I like to really determine the accuracy of a rifle/barrel. 5x5 or 6x5 agg to show how CONSISTENTLY accurate said gun/barrel is.
 
Following - bought two 6.5 barrels from Bartlein today - they just shoot amazing

my personal gun is a Krieger Was a 260 and now rechambered 6.5CM as well- it shoots one hole at 100 (.75 inch at 400 yards)

41.5 grains H4350 -139 scenars lapua and hornady brass - Federal 205M- 210M
What's up Dave longgg time no speak my Ninja ;)

Mike R.
 
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And to add to my last post, we have a heavy block of steel base for the barreled action in the works thanks to @LibertyArms . More details once its complete but essentially a heavy block of steel, bolted and/or clamped to shooting bench with a permanently attached vblock to allow Rem700 style actions to bolt right in. Hoping to have it ready by the time all loads are worked up and confirmed for final 5x5 or 6x5 with both the final loads and again with factory FGMM....
 
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Did I miss something? I thought this was being done using an XLR chassis? What drove the decision to use a test fixture? Does that support the “real world data” approach? Isn’t the reason “We all know you can shoot 1 five shot group that is one hole, etc. but Ive yet to see anyone do it 5x or 6x in a row.” in part because of the physiological and psychological factors that will now be irrelevant? I understand that is the point of a test fixture but I also think it changes things. Just curious. I’m excited to see the results and grateful that Padom has the time and equipment to do the work.

Slow your role big guy. I didnt say I WASNT shooting from my xlr chassis. If you read the entire thread you will see i said that I may shoot out of a fixture as well if that comes to fruition at the very end

Chassis 5x5 or 6x5 will will be shot first
 
Slow your role big guy. I didnt say I WASNT shooting from my xlr chassis. If you read the entire thread you will see i said that I may shoot out of a fixture as well if that comes to fruition at the very end

Chassis 5x5 or 6x5 will will be shot first
I'm looking forward to your test and results. I'm sure you can shoot, but I want to see what happens when the rifle is shot from the fixture. Eliminating as much human error as possible is a great idea.
 
I'll throw this in here as well.

AI did a test just like a year or so ago for they're teams PRS guns. Half the guys wanted 4 groove and the other half wanted 5R rifling (6mm barrels mostly and some 6.5's).

Anyways they ordered a batch of barrels and tested side by side both the 4 groove and the 5R barrels.

Guess what? They found no accuracy difference. So the next time they ordered team barrels there was no spec. for the number of grooves. So I asked them to confirm what they wanted. All 5R he said. Done messing around with it.

Also all of the barrels we make AI for the production rifles are all 5R by the way as well. Has been for years.

Later, Frank
Bartlein Barrels
 
Slow your role big guy. I didnt say I WASNT shooting from my xlr chassis. If you read the entire thread you will see i said that I may shoot out of a fixture as well if that comes to fruition at the very end

Chassis 5x5 or 6x5 will will be shot first



Just saw the “for final 5x5 or 6x5 with both the final loads and again with factory FGMM....”

Sorry
 
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I'm looking forward to your test and results. I'm sure you can shoot, but I want to see what happens when the rifle is shot from the fixture. Eliminating as much human error as possible is a great idea.
This ^^.

Isolate the system with only one variable...the barrel...changing. Only real way to get unassailable data on barrel performance differences due only to rifling difference.

kind of a basic of investigational testing.
 
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This ^^.

Isolate the system with only one variable...the barrel...changing. Only real way to get unassailable data on barrel performance differences due only to rifling difference.

kind of a basic of investigational testing.
It would be a good idea to shoot the best reloads in a particular barrel in the other barrel. I wonder what the results of that test would be.
 
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It would be a good idea to shoot the best reloads in a particular barrel in the other barrel. I wonder what the results of that test would be.

Yep, there will be some of that.

Gonna try and test as many things as possible but I will have to draw a line somewhere. Components and time are not unlimited for this project
 
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I put 100 rounds of new Lapua brass through this Krieger 4 groove barrel this week with 41.8g 4064 and 175smk. At 50rd, I cleaned the barrel by putting some wet patches of Boretech C4 Carbon Scrubber, 4 strokes with a wet bronze brush then another wet patch, then I dry patched it out.

Today I dry tumbled the brass, sprayed the brass in a bin with my Lanolin/99% alcohol mixture and let sit 15min. I then used a Mighty Armory universal decapping die and Mighty Armory FL 308 sizing die, in a dedicated brass prep toolhead on my Dillon 550c set to bump the shoulders back .002". I then dry tumbled them again for 1hr to remove the lube.

After tumbling, I trimmed all the brass to 2.005" and chamfer/deburred the case mouths. Loaded all the brass up using my 21st Century click adjustable hand primer with CCI 450s.

Loaded up 10rd of IMR 4064 41.8gr with a 175smk for foulers. I then loaded up 3rd each from 41.6 - 42.4 in 0.2gr increments for the 175 SMK. They were all loaded on my Dillon 550c using a Whidden Floating die toolhead, Uniqutek clamp kit, Area419 Funnel with 1 drop tube and Dillon adapter on the powder die. Powder was measured on an A&D Fx120i with latest AutoThrow and AutoTrickler.

I then seated all 175smk to .02" off the lands with a Forster Ultra Micrometer seating die.

I loaded a second OCW using the same setup/toolhead, same powder, brass and primers, but used 175 TMK's this time. I loaded 5rd for foulers with 41.6gr IMR4064. I then loaded 3rd each from 41.4 - 42.2gr in 0.2gr increments. You will notice, I went .2gr lower than the 175smk. I did this because the TMK's are much longer and take up more case capacity being down farther in the case. Didnt want to use compressed loads

The 175 TMK's are MUCH MUCH longer than the 175 SMK. For reference, the 175 SMK touch the lands in this 308 Bisley chamber at 2.80 and the 175 TMK touches the lands at 2.93" COAL. So you can really see how much longer these TMK's are than the SMK's. I also loaded the 175 TMK OCW at .02" off the lands so 2.91" COAL. Im running ARC mags so I have plenty of room in the mag for these rounds.

This entire test was shot prone with MDT Cyke bipod and rear bag at 100yd. Temp 75F, Humidity 48%. Wind was 0-5mph

I DID shoot everything over the Labradar like always. Unfortunetly when I left the range I put the SD card in my pocket and had to make a few stops before heading home. Somewhere, I lost the thing pulling keys, wallet, etc out of my pocket. Not happy about it but is what it is at this point. This test is for accuracy so we have that info here.

First up, I shot the 10rd of 175smk foulers at the bottom of the target in 2 groups. Group on the left was the first and the high shot I still had my turret set for 200yd so thats why that first shot out of the rifle went so high. After shooting the 10 foulers, I shot the top row OCW charges from left to right in round robin style letting the barrel cool between strings.

Look at the POI's, I would say the node is 41.8 to 42.2 and I would choose 42gr as my load, regardless of if being the smallest group. Ill do a seating depth test with that next but its already showing good accuracy.









I let the gun cool down completely before moving on to the 175 TMK OCW. Once cooled down 100% I shot the 5 foulers at the bottom of the target. Heck of a 5 shot group.

I then shot the top row from left to right, round robin style, letting the barrel cool between strings just like the first OCW. Looking at POI, it looks to be a pretty wide node from 41.4gr - 42.0gr but really it looks pretty darn forgving across all the charge weights. No real major POI shift form any of the charges. Id probably go 41.7gr. I will do a seating depth with this one as well but as consistent as it was across all the charge weights Im not sure we are going to see a drastic group size reduction...

I do remember the lower end nodes for these 175 TMK's were in the 2585 - 2600 and 42.0 was 2633 and 42.2 was 2628 (yes it dropped even though it was a higher charge). Observation was they were roughly 10-15fps slower for each charge then the 175 SMK's.

After seeing how well these combos shot, Im pretty set on these 2 combos for the test. I dont see any reason to mess with more powders and bullets seeing the accuracy we are seeing with these 2 tests.










 
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I wonder how many people have an opinion on which type of barrel shoots the best, and, I wonder how many of those people will change their mind if the results of this test is different than their opinion.
 
Padom, do you normally see that level of improvement with the TMKs over the SMKs?


Yes

This is the first time I shot TMK's in 308, but I've shot the 223 69 and 77 TMK, 308 125 TMK in 300blk, 130 TMK in 6.5 and 95 TMK in 6mm and they ALL shot lights out so I had high hopes for these 175 TMK. They didn't disappoint. I have the 168 TMK's ill play with at some point too but I have no doubt they will shoot just as well.
 
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I put 100 rounds of new Lapua brass through this Krieger 4 groove barrel this week with 41.8g 4064 and 175smk. At 50rd, I cleaned the barrel by putting some wet patches of Boretech C4 Carbon Scrubber, 4 strokes with a wet bronze brush then another wet patch, then I dry patched it out.

Today I dry tumbled the brass, sprayed the brass in a bin with my Lanolin/99% alcohol mixture and let sit 15min. I then used a Mighty Armory universal decapping die and Mighty Armory FL 308 sizing die, in a dedicated brass prep toolhead on my Dillon 550c set to bump the shoulders back .002". I then dry tumbled them again for 1hr to remove the lube.

After tumbling, I trimmed all the brass to 2.005" and chamfer/deburred the case mouths. Loaded all the brass up using my 21st Century click adjustable hand primer with CCI 450s.

Loaded up 10rd of IMR 4064 41.8gr with a 175smk for foulers. I then loaded up 3rd each from 41.6 - 42.4 in 0.2gr increments for the 175 SMK. They were all loaded on my Dillon 550c using a Whidden Floating die toolhead, Uniqutek clamp kit, Area419 Funnel with 1 drop tube and Dillon adapter on the powder die. Powder was measured on an A&D Fx120i with latest AutoThrow and AutoTrickler.

I then seated all 175smk to .02" off the lands with a Forster Ultra Micrometer seating die.

I loaded a second OCW using the same setup/toolhead, same powder, brass and primers, but used 175 TMK's this time. I loaded 5rd for foulers with 41.6gr IMR4064. I then loaded 3rd each from 41.4 - 42.2gr in 0.2gr increments. You will notice, I went .2gr lower than the 175smk. I did this because the TMK's are much longer and take up more case capacity being down farther in the case. Didnt want to use compressed loads

The 175 TMK's are MUCH MUCH longer than the 175 SMK. For reference, the 175 SMK touch the lands in this 308 Bisley chamber at 2.80 and the 175 TMK touches the lands at 2.93" COAL. So you can really see how much longer these TMK's are than the SMK's. I also loaded the 175 TMK OCW at .02" off the lands so 2.91" COAL. Im running ARC mags so I have plenty of room in the mag for these rounds.

This entire test was shot prone with MDT Cyke bipod and rear bag at 100yd. Temp 75F, Humidity 48%. Wind was 0-5mph

I DID shoot everything over the Labradar like always. Unfortunetly when I left the range I put the SD card in my pocket and had to make a few stops before heading home. Somewhere, I lost the thing pulling keys, wallet, etc out of my pocket. Not happy about it but is what it is at this point. This test is for accuracy so we have that info here.

First up, I shot the 10rd of 175smk foulers at the bottom of the target in 2 groups. Group on the left was the first and the high shot I still had my turret set for 200yd so thats why that first shot out of the rifle went so high. After shooting the 10 foulers, I shot the top row OCW charges from left to right in round robin style letting the barrel cool between strings.

Look at the POI's, I would say the node is 41.8 to 42.2 and I would choose 42gr as my load, regardless of if being the smallest group. Ill do a seating depth test with that next but its already showing good accuracy.









I let the gun cool down completely before moving on to the 175 TMK OCW. Once cooled down 100% I shot the 5 foulers at the bottom of the target. Heck of a 5 shot group.

I then shot the top row from left to right, round robin style, letting the barrel cool between strings just like the first OCW. Looking at POI, it looks to be a pretty wide node from 41.4gr - 42.0gr but really it looks pretty darn forgving across all the charge weights. No real major POI shift form any of the charges. Id probably go 41.7gr. I will do a seating depth with this one as well but as consistent as it was across all the charge weights Im not sure we are going to see a drastic group size reduction...

I do remember the lower end nodes for these 175 TMK's were in the 2585 - 2600 and 42.0 was 2633 and 42.2 was 2628 (yes it dropped even though it was a higher charge). Observation was they were roughly 10-15fps slower for each charge then the 175 SMK's.

After seeing how well these combos shot, Im pretty set on these 2 combos for the test. I dont see any reason to mess with more powders and bullets seeing the accuracy we are seeing with these 2 tests.











Those TMK groups are impressive. Good shooting!
 
This ^^.

Isolate the system with only one variable...the barrel...changing. Only real way to get unassailable data on barrel performance differences due only to rifling difference.

kind of a basic of investigational testing.
You would think so but it doesn't always work like this. I shot small bore for a while and testing ammo is a big thing with 22lr because you can't reload. The groups being shot out of test rigs are much worse than what the best shooters in the world are shooting. Unless things have changed a test rig would be lucky to even make a final at a world cup. And would have a hope of winning. The guys shooting bench rest are shooting much smaller groups even at club level. This makes zero sense to me but somehow it happens
 
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You would think so but it doesn't always work like this. I shot small bore for a while and testing ammo is a big thing with 22lr because you can't reload. The groups being shot out of test rigs are much worse than what the best shooters in the world are shooting. Unless things have changed a test rig would be lucky to even make a final at a world cup. And would have a hope of winning. The guys shooting bench rest are shooting much smaller groups even at club level. This makes zero sense to me but somehow it happens

Was anything about them using test rigs ever published? It doesn't make sense to me either how a good, relatively immovable test rig would be worse than a human.
 
I wonder how many people have an opinion on which type of barrel shoots the best, and, I wonder how many of those people will change their mind if the results of this test is different than their opinion.
My guess would be zero people. You get good barrels and bad barrels from most company's. The only way it would matter is if you had a sample of at least 10s of barrels if not 100s and consistently saw similar results for each. This is why some gunsmiths profer certain barrels. Maybe the techniques they use lend them selves better to getting better results out of certain barrels. Maybe they just like what they like. My gunsmith is very fussy and will only chamber a few brands of barrel and profers particular brands. What I read online won't change his opinion one little bit. I also don't test anything at 100m because accurate rifles are too hard to tell the difference between a good and bad group and we don't shoot at 100m so accuracy there doesn't worry me
 
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Was anything about them using test rigs ever published? It doesn't make sense to me either how a good, relatively immovable test rig would be worse than a human.
Not sure surely there would 've documentation somewhere. I've only seen it in person but people talked about it like it was a common fact. I actually had a conversation about it with someone who shot in the Olympics and his opinion was that not allowing the rifle to recoil freely produced bad groups. Hence on a bench rest the rifle can still recoil but is designed to track exactly the same every time and rhey shoot some incredible groups.
I have nothing to back that up and maybe things have changed. My info is from 12 years ago but I would be very suprised given guns haven't changed
 
^^^^^

Thanks for bring that up McMillan. I’ve heard the same thing from both small bore shooters and the benchrest dudes I’ve shot with. Prohibiting a rifle from moving with the recoil impulse doesn’t seem to produce the best performance. I’ve never seen a serious accuracy nut using a Lead Sled, I suspect for the same reason. Now I’m suddenly hoping there is time and ammo left to shoot from the fixture and see.

Nice shooting PADOM. The increase in the size of the “node” with TMKs is worth noting, for sure. It’s going to be damn hard to figure if any improvement is related to the barrel when the baseline group size is in the .2xxs.
 
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Not sure surely there would 've documentation somewhere. I've only seen it in person but people talked about it like it was a common fact. I actually had a conversation about it with someone who shot in the Olympics and his opinion was that not allowing the rifle to recoil freely produced bad groups. Hence on a bench rest the rifle can still recoil but is designed to track exactly the same every time and rhey shoot some incredible groups.
I have nothing to back that up and maybe things have changed. My info is from 12 years ago but I would be very suprised given guns haven't changed

This is all speculation and hearsay.

@Frank Green can speak more on this, but Bartlein builds tons of ammunition test barrels that are shot out of a test fixture with excellent accuracy results from my conversations with Frank. Manufacturers use these fixtures with test barrels for bullet and ammo testing. They arent shooting a chassis/stocked rifle, BR rig, etc for their testing, all are out of a test fixture. If there was an accuracy problem with a test fixture, they would be using something else....

We will find out once I have the test fixture in hand, I work off data and facts, not what someone told me some time somewhere.
 
Not sure surely there would 've documentation somewhere. I've only seen it in person but people talked about it like it was a common fact. I actually had a conversation about it with someone who shot in the Olympics and his opinion was that not allowing the rifle to recoil freely produced bad groups. Hence on a bench rest the rifle can still recoil but is designed to track exactly the same every time and rhey shoot some incredible groups.
I have nothing to back that up and maybe things have changed. My info is from 12 years ago but I would be very suprised given guns haven't changed

There may be some validity to this as Rail Guns free recoil.

 
I'll throw this in here as well.

AI did a test just like a year or so ago for they're teams PRS guns. Half the guys wanted 4 groove and the other half wanted 5R rifling (6mm barrels mostly and some 6.5's).

Anyways they ordered a batch of barrels and tested side by side both the 4 groove and the 5R barrels.

Guess what? They found no accuracy difference. So the next time they ordered team barrels there was no spec. for the number of grooves. So I asked them to confirm what they wanted. All 5R he said. Done messing around with it.

Also all of the barrels we make AI for the production rifles are all 5R by the way as well. Has been for years.

Later, Frank
Bartlein Barrels

Tough to outshoot an ai with a bart barrel!