lmt 6.5 creedmoor ar 10, 20 inch barrel loading questions

[Eeegadd]

My research shows that the most common brass that 6.5 creedmoor shooters are using has the small rifle primer (magnum)pocket instead of the large primer pocket (non magnum primer). It looks like they're getting higher velocities out of the smaller primer pockets. I've read articles claiming that that my lmt ar10 6.5 creedmoor causes problems with these small primer pockets. Any intel? I guess the firing pin is too big on my gun that cause problems on the primers? Knowing that my gun is only good for about 1400 yds, should I even be worried about this? Does it even matter since I'm not able to reach a mile effectively?

On another note, considering the magazine and reloading to fit the magazine, is it even worth it to trim the necks?

Thank you!

 

[bllistc]

Yes the factory firing pin is too large for small rifle primers. Speaking from experience. The small primer will crater and extrude around the firing pin. You will get pressure signs at very mild loads and probably will not get more than 2 firing from the brass because the primer pockets will be stretched out very quickly. I would recommend just going with large primer brass for the LMT. If you get the JP enterprises bolt carrier and high pressure bolt assembly, those may allow you to use small primer brass but please do not quote me on that. JP is DPMS pattern parts and the LMT is SR25/AR10 pattern. Do not put a DPMS bolt into an AR10 bolt carrier.

I think for most shooters, myself included, you will not notice much difference between the large and small primer brass. The small primers can give you better SD/ES. My loads went from an SD ~5 with small primers to SD 7-9 with large primers. The primer itself doesn't have much to do with reaching a mile. Lower SDs should decrease your vertical spread which means you should have a better chance of hitting a target at ELR ranges. I'm just not sure that small a difference that such as I have seen would be significant enough to change your chances of a hit. I can definitively tell you that shooting out to 1000 yards for PRS matches or similar, large primer brass is absolutely fine.

For precision/match ammo, trim necks each time to as uniform length as possible. I do mine to +/- 0.002"
A longer neck means more tension on the bullet due to the brass gripping it. This can translate to less consistent ammo (higher ES/SD) so worse accuracy at distance.

 

[Eeegadd]

Thank you!! Do you have any intel on loading recipe's? It looks like the brass is all over the board of which I'm leaning towards lapua. h4350 is really hard to find but if you do, it's super expensive. any knowledge on

VihtaVuori N133 Powder? What bullets does t your lmt 6.5cm like? I have imr 4350. Any intel on seating, neck trimming thickness? Thanks a ton!​

 

[bllistc]

Thank you!! Do you have any intel on loading recipe's? It looks like the brass is all over the board of which I'm leaning towards lapua. h4350 is really hard to find but if you do, it's super expensive. any knowledge on

VihtaVuori N133 Powder? What bullets does t your lmt 6.5cm like? I have imr 4350. Any intel on seating, neck trimming thickness? Thanks a ton!​

I use starline brass and it shoots 0.3-0.75 MOA consistently for 5 shot groups with 142gr SMKs and 140gr ELD-Ms. The ELD-M seems to perform better at longer ranges for me. Lapua brass is fine, I just don't think its going to give me a significant enough improvement to justify twice the cost of starline brass. H4350, RL16 or RL17 seem the be the main three powders used for 6.5 creedmoor. I use H4350 myself.

Are you asking about trimming the case or neck turning the brass? I addressed trimming the case in the last post. For lapua brass, you should not need to turn the necks.

 

[Eeegadd]

My mistake, wrong verbage. Neck turning the brass. With either starline or lapua, no need for neck turning? Mmmm ok. How about seating vs fitting the magazine? I've read a few articles where a large number of competitors are just using factory hornady and Berger. Thanks for all your help! You're the best.

 

[bllistc]

Neck turning is a bit of a contested topic on here. I personally don't with starline and lapua. With high quality brass, you probably wouldn't need to. You can play with seating depth for handloads even with the mag.

 

[Klay23]

I use starline brass and it shoots 0.3-0.75 MOA consistently for 5 shot groups with 142gr SMKs and 140gr ELD-Ms. The ELD-M seems to perform better at longer ranges for me. Lapua brass is fine, I just don't think its going to give me a significant enough improvement to justify twice the cost of starline brass. H4350, RL16 or RL17 seem the be the main three powders used for 6.5 creedmoor. I use H4350 myself.

Are you asking about trimming the case or neck turning the brass? I addressed trimming the case in the last post. For lapua brass, you should not need to turn the necks.

Have you found a consistent length of the brass case that works better than others for trimming ? Meaning what length do you trim your brass to before reloading

 

[Maurygold]

Have you found a consistent length of the brass case that works better than others for trimming ? Meaning what length do you trim your brass to before reloading

Trim length will not magically give you accuracy.

To determine trim length: Measure 10 cases. Remesaure the 10 cases. a thousandths under the shortest is what you want.