6.5 Creedmoor

[S3th]

I was able to pick up an 8-lb jug of IMR 4955 over the weekend. Anyone have any experience with it for 6.5 Creed?

No. However, my brother chose that for his 270 heavies. I’m sure it will work well with the heavier 6.5s.

While I’m at it, I have some bullets listed for sale (haven’t gotten around to listing my 140 ELDMs) but if anyone is in need of bullets I will offer a discount to anyone from this thread.

I have 500x 147 ELDMs, 500x 144 LRHT, and 900x 140 ELDMs. All same lots. Message me if your interested and I’ll give you my best price.

 

[260284]

I was able to pick up an 8-lb jug of IMR 4955 over the weekend. Anyone have any experience with it for 6.5 Creed?

4451 is the IMR that is closest to H4350.

 

[SDGator]

4451 is the IMR that is closest to H4350.

I would have loved if they had that. This was the one rifle powder they had, and a quick look at Hogden's online load website showed there is load data for this powder and cartridge, so I took a chance. It'll be interesting to see how it shoots.

 

[ColoradoMTBer]

Hey guys, does anyone know of any good websites I could sell my 6.5cm brass? I cant on here b/c I dont have the rights, reddit doesn't allow it, don't want to pay for an account on arms list. Ebay?

 

[John Glidewell]

Hey guys, does anyone know of any good websites I could sell my 6.5cm brass? I cant on here b/c I dont have the rights, reddit doesn't allow it, don't want to pay for an account on arms list. Ebay?

Just pay for contributing membership here, then you have access to Px.

 

[sifer0425]

wondering if anyone is using 147 grain eld match hornady ? got in 3 boxes and wouldlike to use them for a match at 600 meters. using a ibi 26 inch barrel

 

[DMP]

they had told me 2.80 coal, 38 to 42.3 grains of h4350 powder. that was about it

I am running two 6.5CM right now.
One at 2805, the other 2830 fps. SD 6-7, Sub 1/2". Both loaded the same as follows:

144 Berger
41.5 H4350
Lapua SRP
CCI 450
I loaded OAL from 2.890 down to 2.80. My guns did not like the high or low. But they both love 2.855 OAL.

 

[NamibHunter]

wondering if anyone is using 147 grain eld match hornady ? got in 3 boxes and wouldlike to use them for a match at 600 meters. using a ibi 26 inch barrel

Have used them in a Savage 12 LRP and got amazing groups at 600 yards with over 2,000 rounds on the barrel. Good BC, but the 6.5 CM struggles to get it much beyond 2700 fps using H4350. The double base powders might get you closer to 2750-2780 fps, of course, these powders are famous for faster barrel erosion. Hornady lists RL-26 and PowerPro 4000 MR as the two powders that gets the best speed (2750 or maybe a little more).

The 147 ELDMs are too long for my other two rifles, sits too deep in the case, and you hear a crunch when you seat the bullet. Single feed only.

It is probably better suited for the 6.5 PRC, but depending on freebore and throat erosion, it can sometimes work remarkably well in the Creed too.

 

[harry_x1]

Re: **6.5 Creedmoor Loads**

140 Amax at 2.810" OAL
41.9gr H4350
CCI 200 primers
21.9" barrel

Shoots in the 2's consistently up close and 1/4-1/3 MOA at 600yd, once in a while I get groups at 100 that look like this:

my guess is that the shorter barrell leads to better accuracy, especailly at short/medium ranges. My 338 shoots like a laser from a 20 inch barrell, not the same from 26".

 

[NamibHunter]

my guess is that the shorter barrell leads to better accuracy, especailly at short/medium ranges. My 338 shoots like a laser from a 20 inch barrell, not the same from 26".

Yep: Short 18-22” barrels with large diameter (1.25” or even 1.35”) can be incredibly stiff and shoot tiny groups - if it was properly chambered and bedded to the stock. What you lose in speed and therefore higher dispersion due to wind drift can be recovered (regained) over the shorter distances by better inherent rifle accuracy. Run a Litz WEZ analysis, and you can determine at what distance the quadratic wind drift effect overwhelms the linear MOA benefit. [Wind drift is proportional to distance squared. Angle error resulting from inherent rifle accuracy (say the gun is consistently capable of 0.15 MOA at 100) scales with distance (raised to the power 1), so a linear effect. Wind dominates at long range.]

A rail gun meant for 600 yard BR heavy gun competition that shoots in the ones and zeroes (<0.199” group size) will often have rediculously large barrel diameter, and weight, and you never see a rail gun with a 36” barrel. On the other hand, an ELR rifle meant for 2,500 to 3,500 yard competition will often use 32-36” barrels, but they will not typically shoot 0.1” groups with monos. As always, there are trade-offs.

Example: I have a 30” 6.5 mm bull barrel (1.0” diameter) made by a top barrel maker, and at 100 it shoots at best 0.5-0.7” groups, but at 600-1000 yards it performs really well on 1 MOA steel targets, using high BC bullets and specialized powders. [BTW: The top speed powders listed in the Hornady load manual (developed via testing on 24” barrels) were not ideal for the 30” barrel. Look at the powders listed for a bullet weight 10-15 gn heavier. ]. My 26” barrels outperform the 30” barrels out to 500, maybe even 600, but after 800 yards the rifle with the long barrel seems to win.

And only some actions and stocks are made to handle such long heavy barrels, which is why gunsmiths will sometimes use a barrel block setup with the action “free floated”. Not common, but you occasionally see one at King of Two Miles.

 

[harry_x1]

Yep: Short 18-22” barrels with large diameter (1.25” or even 1.35”) can be incredibly stiff and shoot tiny groups - if it was properly chambered and bedded to the stock. What you lose in speed and therefore higher dispersion due to wind drift can be recovered (regained) over the shorter distances by better inherent rifle accuracy. Run a Litz WEZ analysis, and you can determine at what distance the quadratic wind drift effect overwhelms the linear MOA benefit. [Wind drift is proportional to distance squared. Angle error resulting from inherent rifle accuracy (say the gun is consistently capable of 0.15 MOA at 100) scales with distance (raised to the power 1), so a linear effect. Wind dominates at long range.]

A rail gun meant for 600 yard BR heavy gun competition that shoots in the ones and zeroes (<0.199” group size) will often have rediculously large barrel diameter, and weight, and you never see a rail gun with a 36” barrel. On the other hand, an ELR rifle meant for 2,500 to 3,500 yard competition will often use 32-36” barrels, but they will not typically shoot 0.1” groups with monos. As always, there are trade-offs.

Example: I have a 30” 6.5 mm bull barrel (1.0” diameter) made by a top barrel maker, and at 100 it shoots at best 0.5-0.7” groups, but at 600-1000 yards it performs really well on 1 MOA steel targets, using high BC bullets and specialized powders. [BTW: The top speed powders listed in the Hornady load manual (developed via testing on 24” barrels) were not ideal for the 30” barrel. Look at the powders listed for a bullet weight 10-15 gn heavier. ]. My 26” barrels outperform the 30” barrels out to 500, maybe even 600, but after 800 yards the rifle with the long barrel seems to win.

And only some actions and stocks are made to handle such long heavy barrels, which is why some gunsmiths will use a barrel block setup with the action “free floated”. Not common, but you occasionally see one at King of Two Miles.

thanks a ton for sharing your knowledge on this topic. I found it supremely educative. If I may ask, can you state what will be like an ideal rifle and ammo set up for the king of 2 mile type competition? I would like to try some of those ridiculous distances.

 

[NamibHunter]

thanks a ton for sharing your knowledge on this topic. I found it supremely educative. If I may ask, can you state what will be like an ideal rifle and ammo set up for the king of 2 mile type competition? I would like to try some of those ridiculous distances.

Have a look at this interview with Paul Phillips:



Btw 6.5 Creedmoor would not be a good choice. Think 375, 416, 458 or 50 cal. The various 338 calibers are not really competitive anymore in ELR Heavy Gun. Some of the calibers used at a recent ELR event (Clarke’s Knob):

Two competitors hit the target at over 4,200 yards:

American riflemen make 2.4-mile shot at Clark’s Knob ELR Match in US - Calibremag.ca

How good of a shot are you? Maybe you can shoot dime-sized groups with your Cooey …

calibremag.ca

 

[Slickrick0999]

Currently running Hornady 140 BTHP @ 2800fps and Hornady 140 ELD @ 2780.
Both using H4350 in a 26" Bartlein

 

[newageroman]

Very interesting and thanks for sharing. My 1k gun doesn't group >.5 MOA at 100 but who cares.

I just did some 100 yd groupings to test some ammo that I used harder primers with to get more speed. The lowest speed of the 3 groups also had the smallest group size. I'm on the fence about loading up a bunch of brass to max speed or use the group with the best group size. I think in this case I will lean to smaller group size mainly to try to stay in the node during fast fire (AR-15 6mmARC).

I'm also interested in seeing the barrel block with free floated action setup. that's thinking outside the box!

 

[NamibHunter]

Very interesting and thanks for sharing. My 1k gun doesn't group >.5 MOA at 100 but who cares.

I just did some 100 yd groupings to test some ammo that I used harder primers with to get more speed. The lowest speed of the 3 groups also had the smallest group size. I'm on the fence about loading up a bunch of brass to max speed or use the group with the best group size. I think in this case I will lean to smaller group size mainly to try to stay in the node during fast fire (AR-15 6mmARC).

I'm also interested in seeing the barrel block with free floated action setup. that's thinking outside the box!

Example of a custom barrel block rifle (not my rifle!) built for King of 2 Miles. The block is firmly bedded to the stock, and the shorter section of barrel beyond the block acts (vibrates) like a short stiff barrel. Action is also free floated, so not touching the stock. Benefit of a long barrel in terms of speed and wind drift, but mechanically it behaves like a short stiff bull barrel rifle.

.338 Lapua Magnum Improved Barrel Block Beast for K02M « Daily Bulletin

Report by Corbin Shell Not long ago, I learned of the King of 2 Miles (KO2M) shoot held in Raton, NM and was fortunate enough to get an entry slot. I will be shooting with David Tubb, multi-time High Power and Long Range National Champion, on a team we...

bulletin.accurateshooter.com

 

[NamibHunter]

Well….. All the “good” 6.5 Creedmoor powders remain scarce, so buying what becomes available.

Picked up Alliant PowerPro 4000 MR, and wanting to try it in 6.5 Creedmoor, 308 Win, 300 WSM, and 30-06.

General consensus on the forums seem to be that you get good speed and good accuracy. Alliant calls it a “moderately temperature stable powder”. It appears to be optimized for magnum calibers, and the MR designation refers to “Magnum Rifle”.

In terms of temperature stability, is is apparently not too terrible but also not the most temp stable either.

What speed changes do you guys see between winter (30 deg F) and mid summer (95 deg F) with the same load?

Also: Has anybody tried it successfully in 6.5 Creedmoor? What was the accuracy and speed (and what is your barrel length)? Any other calibers?

I mostly bought it for the short mag (300 WSM), but i got 8 lbs, so interested in trying it in the other calibers too - when i eventually run out.

The 8 lbs can arrived very recently, and have not had a chance to load for it.

 

[sifer0425]

i've used h4831sc powder, and superformance, ok but not great

 

[Blaiz1]

Re: **6.5 Creedmoor Loads**

140 Amax at 2.810" OAL
41.9gr H4350
CCI 200 primers
21.9" barrel

Shoots in the 2's consistently up close and 1/4-1/3 MOA at 600yd, once in a while I get groups at 100 that look like this:

thats a flat shooter

 

[derek1387]

Anyone reload on a Dillon 550 or 750? ANY TIPS?

 

[greentick]

Anyone reload on a Dillon 550 or 750? ANY TIPS?

Since the 550 manually indexes you can set it up however. I just got into 6.5cm. I ran new starline, just the necks, to uniform the tension. Primed my brass same stroke cycle. Pulled off to charge on a chargemaster lite. Seated at station 3. Light crimp station 4. Anyways, that's what I did. More just to get going in a new caliber (using 2000MR) and form my brass, have fun shooting. Finally got some sta-ball and some bergers and then a bad case of covid that put me in the hospital so all on hold for now.

 

[oldnewguy]

I've been loading pistol ammo for about 10 years, but just getting set up to load .223 and 6.5CM.

In reading about dies, I saw a lot of recommendations for the Redding Type S sizing dies. For the 6.5, I see they have a Type S full length die, a Type S neck die, and a set with both. Is the full size with bushings gtg, or is it preferable to use both?

 

[ShaKr524]

I've been loading pistol ammo for about 10 years, but just getting set up to load .223 and 6.5CM.

In reading about dies, I saw a lot of recommendations for the Redding Type S sizing dies. For the 6.5, I see they have a Type S full length die, a Type S neck die, and a set with both. Is the full size with bushings gtg, or is it preferable to use both?

I would recommend the full length die. It is contested topic but (full length vs neck only) at some point you will want to bump the shoulders back (if not every firing then every few) and that will allow you to do that. If you choose to neck size only my preference is for the LEE collet neck die. Having the full length bushing dies allows you to pull the bushing and use it as a body only die also giving you a lot of flexibility in your setup.

 

[GRM]

Folks - got a notification this afternoon that Brownells has powder in stock - not certain if this is the best place to post this - let me know if there's a better thread.

 

[oldnewguy]

PV has IMR 4350 in stock right now...

 

[LANCER]

Sent out a few this weekend. I'm using N-555 and it seems quite stable in the Texas heat. Running 42 grains pushing 140 Hybrids at over 2800 with no pressure signs. This range has a weird vortex between 800 and 1k and I didn't notice all the shifting winds, so missed a few. Also hard to spot misses with the overgrown berms. Just excuses, I know.

 

[tiger49931]

So question with the H4350 and hornady 140 eldm i see people posting to use 42.5 grains of powder. But the hodgdon resource says the max powder charge is 40 grains? but the sierra book says 41.9. such a difference?

 

[ShaKr524]

So question with the H4350 and hornady 140 eldm i see people posting to use 42.5 grains of powder. But the hodgdon resource says the max powder charge is 40 grains? is it advisable to go out of the gate with a 2.5 grain over max load?

There are variables that need to be considered. What seating depth are you using, primers, case capacity (by brand of cases). Some guys might be running 42.5 grains and not having pressure signs. Others might be popping primers at that load level. Its best to start low and work up unless you have experience with all the components and rifle you are loading for. As an example in my factory Remington barrel (26" 6.5CM) i was running 42.8grains of IMR 4451 and a 140 Hornady BTHP in Hornady cases. No pressure signs (till around 43.2) and very accurate. I replaced that barrel with a Criterion and saw pressure signs at 42.5 with the same powder (same lot of powder even) primers, bullets, and cases. I have seen pressure change significantly just by changing primer brands. This why you will typically see most suggest you start a percentage below book max and begin to work up from there with all the components you plan to be using. Once you have that information it is usually good as long as you don't change anything , i.e primers. bullet brand, case brand. You are really building a system so as soon as you change a variable the system is different. I hope that makes sense.

 

[NamibHunter]

So question with the H4350 and hornady 140 eldm i see people posting to use 42.5 grains of powder. But the hodgdon resource says the max powder charge is 40 grains? but the sierra book says 41.9. such a difference?

No, that is not a good idea.

Chamber dimensions, feebore length and barrel age can also make a big difference: For a fresh barrel with a tight “match chamber”, i see pressure signs around 40.3 grains of H4350 with Lapua SRP cases. Lapua and Norma/Nosler have less case capacity than Hornady, and will hit high pressure a little lower. A round loaded to a hard jam (or with a heavy crimp), might hit pressure 1.5 gn below book max. A round loaded with a long bullet seated way deep inside the case (a heavily compressed load) could also raise pressure, but leas than a jam. Some batches of primers or powder could also spike your pressure.

My new barrels with a SAAMI chamber (Remington 700) hit mild pressure signs at 41.6 gn. Close to the book max value.

Once the barrel gets past 1,800 rounds, when the lands have moved forward, i repeat the pressure test and typically see pressure signs at 0.8 to 1.0 grains higher. After 2,500 rounds, most barrels are toast, and the lands have moved way forward, but if you get lucky and it still shoots, you might find that 1.3 to 1.8 grains more are needed to hit pressure, and recover the lost speed. But YMMV.

Your rifle will almost certainly be different from mine, so start low and work up in steps of 0.3 or 0.5 gn. Heavily cratered primers are often the first signs of pressure.

Also: Watch out for inadvertently “lubricated” cases or a wet chamber (from leftover cleaning liquids), that can sometimes also cause a bright ejector mark (a false positive). I have had a few rounds loaded with Imperial Dry Lube (applied on the bullet only - to mitigate “bullet weld”), where the graphite lube spilled onto the outside of the case, because i forgot to wipe it off properly, and saw a few ejector marks at loads below 40.0. Ammo coming out of a cold air conditioned vehicle can also collect condensation and get wet when you open the box in a very humid environment, giving rise to the same problem.

 

[oldnewguy]

For components, I've bought Lapua SRP brass, CCI 450 primers, some H4350, IMR 4350, Alliant 26, and Win StaBall. Still need projectiles, I think I'll order a mix of BTHP and some 140 or 147 ELD-M.

I ordered the Redding sizing and seater dies mentioned above. And a 550 caliber conversion is on the way.

What else am I missing?

 

[NamibHunter]

For components, I've bought Lapua SRP brass, CCI 450 primers, some H4350, IMR 4350, Alliant 26, and Win StaBall. Still need projectiles, I think I'll order a mix of BTHP and some 140 or 147 ELD-M.

I ordered the Redding sizing and seater dies mentioned above. And a 550 caliber conversion is on the way.

What else am I missing?

Good brass, and a good selection of powders.

I also got good results from the 140 ELDM’s. The 147’s are very long, and success will depend on your freebore length, especially if you load to mag length. May be workable if single feeding the rounds, if you have longer freebore, or if the lands have moved forward due to high round count.

In a new barrel, the boattail might be sitting well below the neck-shoulder junction, possibly compressing the load and limiting how much powder you can use, thus limiting speed. Also, minor donuts can form after 8-10 firings, and that can affect group size and ES. Lapua SRP brass has remarkably long life (20-30 reloads are possible), which is a good thing, but long life means the cases might eventually develop a donut in the neck. [You can cut out the donut with the K&M neck turner every 8-10 reloads, but that has some side effects.]

I would add 144 gn Berger Hybrids to the list of bullets to try, if you can find them. More expensive, but IMHO they are more consistent at longer ranges (>800 yards).

 

[oldnewguy]

Thanks, I was thinking I'd pick up some less expensive bullets for plinking and shooting at shorter distances. Then save the ELD-M and Bergers for long distance stuff.

 

[ShaKr524]

Thanks, I was thinking I'd pick up some less expensive bullets for plinking and shooting at shorter distances. Then save the ELD-M and Bergers for long distance stuff.

I used the Barnes Match Burners at a training out to 1k and they worked very well. I did need to adjust the BC to .550 in Strelock to match up with actual data but they were very consistent. I also have had great luck with the 140 BTHP Match from Hornady. These have worked well enough for me that i have not pursued some of the more expensive options although i am sure they too are excellent.

 

[Slickrick0999]

I have had good luck with the Hornady 140 bthp bullet and great results so far with the 140 eld.
As a side note, the Hornady American Gunner loaded ammo does pretty good. I bought it for the brass really but it is good ammo especially 500 yards and in.

 

[NamibHunter]

I used the Barnes Match Burners at a training out to 1k and they worked very well. I did need to adjust the BC to .550 in Strelock to match up with actual data but they were very consistent. I also have had great luck with the 140 BTHP Match from Hornady. These have worked well enough for me that i have not pursued some of the more expensive options although i am sure they too are excellent.

Yes: The 145 Matchburners worked for me too. It kept me shooting when i could not find anything else. It is fairly easy to find.

Presume you meant a G7 BC of 0.350 (or did you really mean their G1 BC was actually 0.55)? I got a G7 BC closer to a 0.33, but it will vary from rifle to rifle.

 

[ShaKr524]

Yes: The 145 Matchburners worked for me too. It kept me shooting when i could not find anything else. It is fairly easy to find.

Presume you meant a G7 BC of 0.350 (or did you really mean their G1 BC was actually 0.55)? I got a G7 BC closer to a 0.33, but it will vary from rifle to rifle.

I was using the G1. It was listed at .586 but matched up perfect at .550 for me. I have yet to try the 145's but would like to.

 

[NamibHunter]

I was using the G1. It was listed at .586 but matched up perfect at .550 for me. I have yet to try the 145's but would like to.

My apologies, i misread your post. I was referring to the 145 Barnes Matchburners, which has a G1 BC closer to 0.68.

The 140’s should indeed have a G1 between 0.55 and 0.58.

 

[Cardboard Assassin]

I used the Barnes Match Burners at a training out to 1k and they worked very well. I did need to adjust the BC to .550 in Strelock to match up with actual data but they were very consistent. I also have had great luck with the 140 BTHP Match from Hornady. These have worked well enough for me that i have not pursued some of the more expensive options although i am sure they too are excellent.

These gave me the most consistent load I ever used for for my 6.5CM, wish I had bought more (only bought 1000).

 

[ShaKr524]

These gave me the most consistent load I ever used for for my 6.5CM, wish I had bought more (only bought 1000).

Midway currently has 500 count 140 BMB's in stock. They used to be around $.25 each but like everything have gone up about 30%. They are still a few cents cheaper than the Hornady BTHP though and probably the most cost effective long range bullet for the 6.5's I am aware of.

Midway 140 Barnes MB Link

 

[tiger49931]

Anyone have a good load for a GAP crusader using hornady 140 eldm and 4350. i notice they say max load now is 40.2 according to sierra.

 

[sifer0425]

what twist is that a 1/8

Currently running Hornady 140 BTHP @ 2800fps and Hornady 140 ELD @ 2780.
Both using H4350 in a 26" Bartlein

 

[Slickrick0999]

what twist is that a 1/8

Yes

 

[sifer0425]

Yes

how far off the lands do you go i'am at 10thou off the lands how far are you?

 

[acudaowner]

imr 4451 140 gr hornady bthp m bullets 42.0 gr 2737:max 2719 :min and 2729 :avg sd: 9.3 es: 18 I was shocked my starting load gave me that result I was thinking it would be far too slow a powder but was pleasantly surprised just another powder you might choose and from a 26'' barrel ,

 

[sifer0425]

i'am running a ibi barrel 1/8 twist 10thou off the lands getting 2737 on h4350 40.3 grains powder with hornady bthp 140 grain. was wondering if i should push it off the lands some more

 

[sifer0425]

whats your accuraccy like at 400 yards

 

[Slickrick0999]

how far off the lands do you go i'am at 10thou off the lands how far are you?

Man, I hate to say. I honestly don't "really " measure off the lands. I do the Eric Cortina style. I loaded a round and kept seating in deeper until bolt close was what I wanted (smooth). Then used his method on seating depth tuning (and then used his tuner brake as well). As far as a measurement, I use BTOG.

 

[tiger49931]

So i have A GAP TEMPLAR 6.5 I took off the titan break and put on a YHM 7.62 break with qd for my suppressor. Using hornady match ammo i was getting .21 groups to .45 (shooter error im sure) but now with the new muzzle break i ran a satterly extended 5 shot per load ladder 39.1 grains of h4350 to 40.9 grains. best group is like 40.3 grains that had a SD of 10.3 but my 40.9 2715 FPS had a 5.6 sd with a ES of 10 . but no one hole shots that im looking for. Max load according to sierra is 40.6 should i go higher looking for a better more solid node or is it the muzzle break? Do you guys look more at SD or group size? or will the lower SD get you a better group?

 

[Slickrick0999]

So i have A GAP TEMPLAR 6.5 I took off the titan break and put on a YHM 7.62 break with qd for my suppressor. Using hornady match ammo i was getting .21 groups to .45 (shooter error im sure) but now with the new muzzle break i ran a satterly extended 5 shot per load ladder 39.1 grains of h4350 to 40.9 grains. best group is like 40.3 grains that had a SD of 10.3 but my 40.9 2715 FPS had a 5.6 sd with a ES of 10 . but no one hole shots that im looking for. Max load according to sierra is 40.6 should i go higher looking for a better more solid node or is it the muzzle break? Do you guys look more at SD or group size? or will the lower SD get you a better group?

For what it is worth, my 140 bthp load is 42.1 & my 140 eld load is 41.1. Just watch for pressure signs.
I look for velocity flat spots between charges when developing. Usually 2 maybe 3 rounds of each charge weight & on 6.5cm, my first test is 0.3gr increments (I refine after down to 0.1). After that, seating depth testing.

 

[NamibHunter]

For what it is worth, my 140 bthp load is 42.1 & my 140 eld load is 41.1. Just watch for pressure signs.
I look for velocity flat spots between charges when developing. Usually 2 maybe 3 rounds of each charge weight & on 6.5cm, my first test is 0.3gr increments (I refine after down to 0.1). After that, seating depth testing.

Good advice. Once you know max load (to avoid over pressure), you can usually find two flat spots in the speed vs powder charge graph if you look at a 2 grain range. One flat spot is often wider than the other, so pick that one, even if 50 fps slower than max. Repeat in smaller increments (and shoot 3-5 rounds at each powder weight) if you want to make sure it was not just blind luck.

Seating depth optimization can almost always get your groups to tighten up. You may need to look at small jump (3 to 25 thou) in 3-5 thou increments, avoiding a jam, AND try large jump (30-150 thou) in 10-20 thou increments. On a worn barrel you may have to search the 50-250 thou range. Or get a barrel tuner. Deeper bullet seating just adds a small (microsecond) delay in bullet exit time, just enough to allow the barrel to whip upwards and point at the right angle.

Changing out a muzzle brake with one that is lighter or heavier will often mean that whatever factory ammo shot well before, might now shoot groups that are 2-3x bigger, with the exact same ammo. [Group size might also get smaller.] Even locking up your self-timing brake one thread further out than before can cause major accuracy problems

Barrel whip frequency changes with muzzle weight and length. Bullet exit time changes with bullet weight, seating depth, and powder charge (MV) - all contributing to barrel dwell time changes. A good load (optimized via seating depth changes) lines up the bullet exit time with an upswing in the barrel.

You will probably have to try other factory options, usually different bullet weight. Or install a barrel tuner.

 

[Slickrick0999]

Good advice. Once you know max load (to avoid over pressure), you can usually find two flat spots in the speed vs powder charge graph if you look at a 2 grain range. One flat spot is often wider than the other, so pick that one, even if 50 fps slower than max. Repeat in smaller increments (and shoot 3-5 rounds at each powder weight) if you want to make sure it was not just blind luck.

Seating depth optimization can almost always get your groups to tighten up. You may need to look at small jump (3 to 25 thou) in 3-5 thou increments, avoiding a jam, AND try large jump (30-150 thou) in 10-20 thou increments. On a worn barrel you may have to search the 50-250 thou range. Or get a barrel tuner.

Changing out a muzzle brake with one that is lighter or heavier will often mean that whatever factory ammo shot well before, might now shoot groups that are 2-3x bigger. Barrel whip frequency changes with muzzle weight. Bullet exit time changes with bullet weight and powder charge. You will then have to try other factory options, usually different bullet weight. Or install a barrel tuner.

This is almost exactly what I just did.
I wanted to shoot the 140 eld for a better BC. At the same time, I wanted to try out a tuner. I bought a EC Tuner brake and did all of the load development with the tuner set to zero. Once I had my charge and seating depth data, I started playing with the tuner and was able to tighten the group up even more.