PC 155's still need gas checks?

[caliplt]

I'm running an 8 unfortunately!

[gds]

I finnaly got around to trying some of the lee 160gr tl boolits powder coated and with and without gas checks.

9.5 inch 8.5 twist AR15

14.7gr lil gun this is just a plinking load



I was kind of surprised, but it is what it is.

[Dolomite_Supafly]

I will try the same test in my 10 twist gun. I do not have the TL version but I will use the standard lube groove version.

My standard load uses 16 grains of Lil'Gun. That makes it easy because I use 8 grains for all subsonic loads. One throw of the lever for subsonic loads and two throws for supersonic loads.

I am transitioning to IMR4227 from Lil'Gun. Lil'Gun has the smallest SD numbers I have ever seen and it accurate but with some loads the bullet is melting enough to lead a lead ring on the case mouth even with PC bullets. So far I have not seen it with 4227. Hopefully the 4227 can be doubled for supersonic loads like with Lil'Gun.

[caliplt]

Yeah, I'm running the lube groove bullets as well. Still waiting on my PC machine!

[boost]

gds,

I don't have the Lee 160 mold yet. just wondering, is the gas check still in the case neck ? If so, then the OAL is slightly longer vs the 155's.

[gds]

gds,

I don't have the Lee 160 mold yet. just wondering, is the gas check still in the case neck ? If so, then the OAL is slightly longer vs the 155's.

the gas check is not in the case neck.

no with the 160gr TL version it actually is a shorter OAL. I Load the 155gr to 1.970 and the 160gr to 1.930. with the 2 molds that I have the 155 has a steeper ogive then the 160. i think that is typical. i know I have read some things on it being different.

The OAL length seems to do good for feeding out of standard GI mags I had some problems with seating them longer and feeding from GI mags.

i am considering taking out the gas check base on my 155gr mold to work like the accurate mold you have.

EDIT: COL was incorrect should have been 155gr 1.970 and 160 gr 1.930.

[Dolomite_Supafly]

Yeah, I'm running the lube groove bullets as well. Still waiting on my PC machine!

No need for the PC machine. If you have a vibratory tumbler you have everything you need to coat bullets.

[caliplt]

Yeah, I saw your write-up. I spent $150 on the HF kit, compressor, and oven. I'm going to stick to it for a while. At least get my moneys worth. I'm just pissed I have to buy a gas check maker now.

[gds]

OK I revisited this. NOTE: my COL listed above was not correct. I edited the above post to reflect the correct COL

First off the old COL I used is not good for 16gr of Lil gun. Blew out 2 primers. not cool. my fault. I should have have Known better. Rounds were not feeding and the 155s were grouping horrible. was about to throw my rifle and reloading stuff in the garbage.

Looked again and realized my COL was wrong. 16gr is not a problem with the correct COL. Just don't use the COL I listed above.



In going back down to 14.7 gr and 1.970 for the 155gr gas checked and 1.930 for the 160gr gas checked things improved except in the non gas checked 160gr. The non gas checked 160gr boolits were horrible. of 5 shots only 3 hit the paper and one of those was sideways. Thankfully I did not have a baffle strike. because I am pretty sure the other 2 that missed were tumbling also.



Now the 155gr gas checked as well as the 160gr gas check performed fine. You will notice that they are kind of in the same group except the one to the top right, and that could have been me.

I Cannot figure out why these 160gr non gas checked performed so horribly today. I mean I knew they were not accurate, from previous testing. but this was just horrible. I will not be shooting these again till i put a gas check on them

[yondering]

I Cannot figure out why these 160gr non gas checked performed so horribly today.

Lee's tumble lube designs seem more prone to uneven band shrinkage from a hot mold, and it's harder to spot until it's really bad. They also are prone to being undersized anyway, as well as not sealing the bore as well as a standard lube groove bullet. A gas check helps with the last two.

If you're thinking of going plain base on that mold, it wouldn't hurt to ream the bases to .310-.311, for a better gas seal. No guarantee they'll shoot well that way either though.