Trying to figure out heavy bolt lift and my match load

[EchoDeltaSierra]

I've posted a few threads along the way trying to finalize my match load for what is my first custom barrel rifle.

Components:
Lapua brass w/ CCI BR-4 primers (300 pieces for match ammo)
Nosler Brass w/ CCI BR-2 primers (200 pieces for range/test ammo)
Hornady 140gr ELD bullets
Hodgdon H4350 powder

I've tested my action/barrel combination up to 44gr without adverse pressure signs. I've noticed that I get the same velocities running my Lapua brass as my Nosler brass, so charge weights are the same. I am currently using 43.2gr of H4350 which shoots really well, primers are still rounded, and I get 2810fps validated at 1000y. That said, the lift seems a bit stiff. Would dropping my charge 0.2gr down to 43.0gr make enough of a difference to experiment with? I want to quit messing with this and load up my match ammo for PRS season which starts on 4/27.

Not having played with an action/barrel that can take such a hot load, or a barrel that shoots so well, I'm looking for any ideas or suggestions. Thanks in advance.

 

[Sheldon N]

I've tested my action/barrel combination up to 44gr without adverse pressure signs. I've noticed that I get the same velocities running my Lapua brass as my Nosler brass, so charge weights are the same. I am currently using 43.2gr of H4350 which shoots really well, primers are still rounded, and I get 2810fps validated at 1000y. That said, the lift seems a bit stiff. Would dropping my charge 0.2gr down to 43.0gr make enough of a difference to experiment with? I want to quit messing with this and load up my match ammo for PRS season which starts on 4/27.

Heavy bolt lift is a pressure sign, so can't say that you have no pressure signs.

IMO for a match rig it is FAR more important that the gun run effortlessly and be weather safe for adverse conditions, than any benefit that velocity would get you. I'd gladly give up 100fps just to get that.

Make sure brass is sized appropriately in all dimensions, (headspace and base/shoulder diameter), that it chambers effortlessly without excess headspace (no more than 0.003), and reduce powder charge to the point where you don't notice ANY extra effort on bolt lift. Double check that the load is rain safe by dousing a full mag with water and seeing if you can run wet brass without heavy bolt lift.

That's the range of charge weights you want to look in for an accuracy load.

 

[Sheldon N]

I'll toss out this footage of myself from a match last weekend as an example of lack of bolt lift and the gun running smooth. Pardon my ugly mug and the low video quality, this is just something that someone sent me after the fact.

Stage was 5 targets at different yardages, two positions on a wobbly/teeter totter wooden barrel, 90 seconds. Shoot all 5 targets from position 1 left side of the barrel, transition to right side, then shoot all 5 targets in reverse from position 2. I did it with hold overs since there wasn't really enough time to dial. It's hard to see from the video but that barrel is on a horizontal teeter/totter mount. If I were fighting the bolt for each shot that would have added a bunch of extra instability to the position.

 

[EchoDeltaSierra]

Thanks @Sheldon N for taking the time for a thoughtful reply. I really appreciate the perspective.

 

[LawnMM]

Sounds like headspace to me, check your fired versus unfired cases and make sure you have the requisite .002, I've actually started setting my dies for .003 to .004 for my match caliber because the barrels get replaced and I've been to one match were my stuff was undersized and it made feeding a bitch all weekend.

Was sized after being fired in a different chamber and I didn't check it in the new one. Live and learn.

 

[EchoDeltaSierra]

Sounds like headspace to me, check your fired versus unfired cases and make sure you have the requisite .002, I've actually started setting my dies for .003 to .004 for my match caliber because the barrels get replaced and I've been to one match were my stuff was undersized and it made feeding a bitch all weekend.

Not a feeding issue, it's an extraction issue. Headspace is good; I set it myself. Shoulders are bumped just about .002" and chamber like butter.

 

[BigTex]

43.2 is pretty warm, I started seeing pressure at around 43.6 in my recent workup. I ended up going with 42.5gr ad they shoot lights out, No pressure @2800fps. the 43.4gr-43.8gr loads shot lights out, but the bolt was getting stiff. This was with Bergers, but IME Hornady bullets get to pressure quicker due to the longer bearing surface. YMMV

Here is the thread if you want to check it out.
http://www.snipershide.com/shooting/threads/1-shot-vs-3-shot-ocw-finished-load.6936555/

 

[918v]

This is a combination of load too hot / shoulder too soft.

 

[abn31c]

Id load some at 40 grains and 20 thou off and go from there. My rifle would come apart at 43 grains. If youre velocity in lapua matches nosler thats an issue.

 

[EchoDeltaSierra]

If youre velocity in lapua matches nosler thats an issue.

I’ve consistently seen less than 10fps variance at all charge weights across all load development on two rifles between Lapua+BR-4 and Nosler+BR-2. Curious how this is an issue. Could you expand on this comment? -thnx

 

[PinesAndProjectiles]

What was the temp when you tested loads up to 44 grains?

What is the temp now?

 

[EchoDeltaSierra]

What was the temp when you tested loads up to 44 grains?

What is the temp now?

I was able to test 44gr in 25 degrees, and the 43.2gr in mid 60s. I am tracking temperature variability along the way. Also, well aware of the thermal impact considerations. I’ll be shooting another test today specifically focused on bolt lift. Curious to see the results and I’ll share results on this thread.

 

[918v]

What is your barrel cleaning regimen?

 

[EchoDeltaSierra]

What is your barrel cleaning regimen?

I have less than 200 rounds through this barrel. That said, I clean all my rifle barrels pretty lightly. Couple of passes with wet patches couple of passes with a nylon brush, couple more wet patches until clean, dry patches until no further residue. I only strip copper when needed. That has served me quite well for several rifles/calibers.

 

[Bradu]

I may have overlooked it but what caliber are you shooting?

 

[918v]

Nylon does not clean carbon out if the barrel very well. It just rides over it. Maybe you should clean it wit a bronze brush down to the pores and see if that helps. Or back off the powder to lower the pressure.

 

[EchoDeltaSierra]

I may have overlooked it but what caliber are you shooting?

6.5CR

 

[Subwrx300]

I'm in agreement with some of the others here on charge being a bit on the stiff side for that brass and that the shoulders are likely a bit softer, which is generally good, except when you get to higher pressure charges.

I run Hornady and Starline brass and have experienced exactly what you are describing with Starline. With Hornady, I can shoot 2800-2820 with zero heavy bolt lift and no pressure signs. But if I push Starline beyond 2760-2770+, I get heavier lift on 60-70% of the shots. Both chamber perfectly, but extraction with Starline becomes noticably stiffer even at lower velocity. The shoulders/necks on Starline are much softer (and slightly thicker) than the Hornady and I am 100% this is what's causing the issue.

I'd back load down to 2700-2750 (next node down) and see if issues disappear.

 

[Bradu]

6.5CR

I kind of surprised you were able to load that high on the powder charge.

 

[Mordamer]

I have had excess sizing lube be left on the outside of cases cause stiff bolt lift even on starting loads. Just one thing to check off the list.

 

[EchoDeltaSierra]

I kind of surprised you were able to load that high on the powder charge.

Me too. With the ARC Nucleus action, I started with a used Criterion barrel and ran a .2gr ladder from 41.6 up to compressed over a Magnetospeed. The primers started flattening out around 44.2gr, and I stopped there. At 43.2gr the edged of primers are still rounded.

 

[EchoDeltaSierra]

I have had excess sizing lube be left on the outside of cases cause stiff bolt lift even on starting loads. Just one thing to check off the list.

I tumble in walnut after I prep brass and before I prime to remove the lube.

 

[Subwrx300]

I tumble in walnut after I prep brass and before I prime to remove the lube.

Just something to note, if you use Walnut (as I do also) the super fine powder from new(er) media can be pretty nasty. If you aren't already, toss 3-5 cut up dryer sheets in media to majority remove the dust from the media before tossing in brass.

The dust might be causing some of your issues as it's essentially ultra fine grit dust/dirt that gets pressure blasted between walls of chamber and brass.

Ask me how I know ...? Doh!

 

[Bradu]

From the sounds of things, I would try around 42 grains to see how the bolt feels. I know it won't have the speed you are probably looking for but I think you are going to have troubles when the weather warms up.

 

[abn31c]

I’ve consistently seen less than 10fps variance at all charge weights across all load development on two rifles between Lapua+BR-4 and Nosler+BR-2. Curious how this is an issue. Could you expand on this comment? -thnx

Just my experience, i had a .4 tenths difference in charge weight when I played with nosler. My guess is it would depend on how close to the lands you are. I was jamming at that time.

 

[EchoDeltaSierra]

If you aren't already, toss 3-5 cut up dryer sheets in media to majority remove the dust from the media before tossing in brass.

I learned that tip here. When I tossed the cob media and switched to walnut, I use the dryer sheet trick. Plus, the lavender scent is marvelous.

 

[EchoDeltaSierra]

Ran the test I wanted today since I was already at my range for RSO training. Shot a ladder to evaluate bolt lift. 5 round at 42.2 - 43.0 in .2 grain steps.

Lessons learned. In 40 deg temps, bolt lift began to get a bit harder at 42.8, and was more noticeable at 43.0. The two groups below were 42.4 and 42.6 and extraction was buttery smooth.

Next step will be load a box of 50, chrono 10 for velocity and SD/ES, then true up the kestrel with 1000y drop data.