Crimping Question

[shamu2240]

UPDATE......

So I got out to the range and tested my loads, I did NOT shoot the rounds with the very noticeable crimp. I am a little surprised with what I found out and not sure where to go from here. The problem is that my starting group with 72 grains of powder is about 2.5" at 100 yards. Then I can tell I'm starting to hit pressure with 72.5 grains, slightly heavy bolt lift, with an even worse group. At 72.8 grains the group tightened up a lot 3/4 group at 100. Same with 73 grains but it was a very heavy bolt lift. How do I use this info to guide me on what to do next? Do I try a different powder? O do I go down in charge with the original powder and try messing with the crimp?

300WM / 24" barrel / 166 HH / IMR 4350 / Peterson Brass 2x Fired / CBTO 2.910 (5 tho jump) / labradar

Here's the velocities I got for the powder charges. I loaded 4 rds for each powder charge with the exception of 72.8. I loaded 5 rds for this one. Why did I do that? No idea just seemed like it was going to be a sweet spot to me. I started at 72 grains.

72
1) 3284
2)3202
3)3304
4)3331

72.5 Slightly heavy bolt lift for these 4 rds, you probably wouldn't notice if it wasn't your own rifle.
1)3321
2)3329
3)3338
4)3298

72.8 Little heavy on the bolt lift through these rds but nothing that was jumping out at me as being over the top.
1)3363
2)3327
3)3373
4)3363
5)3368

73
1)3366 Heavy bolt lift
2)3368 Heavy bolt lift
3)3376 VERY HEAVY bolt lift. I stopped and did not shoot the next round.

The other thing that is weird to me is that these numbers don't seem to support what I felt in the gun itself. I feel like the last three shots I took should have been well above those numbers to be giving such a noticeable reaction in the rifle. What do you guys think?

 

[David_h]

Could try charges below 72gr. Might find another accurate node without pressure and still decent velocity.

 

[Laguna Freak]

Could try charges below 72gr. Might find another accurate node without pressure and still decent velocity.

This ^^^

Looks like you need to find the next lower powder charge accuracy node, then fine tune seating depth. Generally, you should be able to find another sub-moa node with a charge spread of .1 to .3 grains. I'd be looking for final velocity ES to be less than 12 fps after finishing seating depth.

 

[Old Rooster]

Laguna Freak hit on my thought.Finding the seating depth of bullets is as important as powder charge and works in unison with powder charge.
I have had some rifles shoot best .005 of lands and others shoot .020 or a lot more off lands.One Barnes load shoots at .060 off lands.
Experiment with depth and try again.By the way,welcome to the deepest rabbit hole but very nice when you find the sweet spot.
BTW remove all, the copper and carbon in that barrel so you can start with a clean barrel.Also keep notes!Note every change.

 

[VinceMule]

Seating depth, in the 7 mags I own, shooting 120-160g nosler ballistic tips, I sort bullets by ogive length, then seat them to barely kiss the lands. By using this method, I get 3/8" and less size groups. In 30 years, I have never stuck a bullet in the barrel using this method that was taught to me by an old German Gunsmith.

I full-length size on every firing of the brass, Rem and Winchester.

Then I ordered a 308 reamer with short freebore, glory be what small groups at 300 yards with 155-175g Sierra's!

I am going to try Mr. Beans method of crimping, as Lee also has different sizes of mandrels which are easily modified, helping with neck tension needed. I know that McMaster Carr also carries different sizes of mandrels that can be held in place with a simple O ring varying in size from .0001 for one class of mandrel to .0005 on another class of mandrel.

 

[ButterBean]

UPDATE......

So I got out to the range and tested my loads, I did NOT shoot the rounds with the very noticeable crimp. I am a little surprised with what I found out and not sure where to go from here. The problem is that my starting group with 72 grains of powder is about 2.5" at 100 yards. Then I can tell I'm starting to hit pressure with 72.5 grains, slightly heavy bolt lift, with an even worse group. At 72.8 grains the group tightened up a lot 3/4 group at 100. Same with 73 grains but it was a very heavy bolt lift. How do I use this info to guide me on what to do next? Do I try a different powder? O do I go down in charge with the original powder and try messing with the crimp?

300WM / 24" barrel / 166 HH / IMR 4350 / Peterson Brass 2x Fired / CBTO 2.910 (5 tho jump) / labradar

Here's the velocities I got for the powder charges. I loaded 4 rds for each powder charge with the exception of 72.8. I loaded 5 rds for this one. Why did I do that? No idea just seemed like it was going to be a sweet spot to me. I started at 72 grains.

72
1) 3284
2)3202
3)3304
4)3331

72.5 Slightly heavy bolt lift for these 4 rds, you probably wouldn't notice if it wasn't your own rifle.
1)3321
2)3329
3)3338
4)3298

72.8 Little heavy on the bolt lift through these rds but nothing that was jumping out at me as being over the top.
1)3363
2)3327
3)3373
4)3363
5)3368

73
1)3366 Heavy bolt lift
2)3368 Heavy bolt lift
3)3376 VERY HEAVY bolt lift. I stopped and did not shoot the next round.

The other thing that is weird to me is that these numbers don't seem to support what I felt in the gun itself. I feel like the last three shots I took should have been well above those numbers to be giving such a noticeable reaction in the rifle. What do you guys think?

First off you are to close to the lands and you are already maxed if you have heavy bolt lift, start over and seat with all the PDR grooves in the case mouth and start with an 1/8th crimp, I'm not a big fan of IMR4350 but that's irrelevant.
I need to know what the case fill is as well just give me a holler 812-264-6183
Bean

 

[BigDon]

First off you are to close to the lands and you are already maxed if you have heavy bolt lift, start over and seat with all the PDR grooves in the case mouth and start with an 1/8th crimp, I'm not a big fan of IMR4350 but that's irrelevant.
I need to know what the case fill is as well just give me a holler 812-264-6183
Bean

Bean has nailed it here. The HH bullets like jump. You're using old school loading logic with a new school bullet. There is HUGE amount of info on these bullets on this forum in outrageous (almost boring) depth. Study up. Believe Bean. Seat these puppies deeper - as Bean advises - and enjoy the results. It's time for you to move into the new world!

 

[Laguna Freak]

Bean has nailed it here. The HH bullets like jump. You're using old school loading logic with a new school bullet. There is HUGE amount of info on these bullets on this forum in outrageous (almost boring) depth. Study up. Believe Bean. Seat these puppies deeper - as Bean advises - and enjoy the results. It's time for you to move into the new world!

This is good stuff ^^^
FWIW, over the last few years I've found that even old school boolits like Accubond and Scirocco II perform most consistently seated .055" to .075" off lands in 3 different rifles/barrels, and the seating depth node is usually at least .002" wide and sometime .003"+.

 

[ARlife4me]

I use a sharpie and do vertical lines from shoulder to half way up the bullet. I triied micing it, but couldn't detect a change. As mentioned in Beans video some are visible and some aren't. It makes you want to crimp it more. The cam over pressure/resistance is the crimp.