Case length, Ogive vs COAL, Smoking barrel.

[ryan500]

Hi, a few questions for the pro's here about 7.62x54r but more reloading in general.

1) My manual calls for trim to 2.105" but my Lee case length gauge goes to 2.114", which should i go for and how does it affect accuracy?

2) Today I shot my first 30 handloads seemed like my barrel smoked a little more than with factory ammo? Could it be the lube?

3) My manual calls for 2.900" COAL with the bullets i'm running, now i haven't measured to my lands yet but i'm sure my COAL will be longer if i seat the bullets lands or back from them .010" or so.

4) If i should seat to the lands, will this increase the pressure of a given load from the origional COAL of 2.900"? And will it improve accuracy or is it a myth?

For info, i'm running PRVI brass, Speer Hot Cor 150 gr, 40.9gr IMR 3031, and Winchester primers.


Thanks, Ryan.

 

[interlock]

Hi ryan,
I am not a pro but pretty experienced.
1) thats fine, no noticeable accuracy effect
2) Maybe the powder you have used is a bit smokier than the factory ammo, also no problem.
3)yes the coal will be longer. leave them .01 off the lands is better than them jamming in, the pressure won't get so high and also you dont have the risk of leaving a bullet stuck in the barrel when you unload a round leaving powder all over the place.
4) don't seat into the lands.

interlock

 

[rcmodel]

Forget seating to the lands.
It won't make one bit of differance in a Mossy.
Just load them to the suggested OAL in your manual.

I don't know what to tell you about using IMR-3031 in the 7.62x54r, but it would seem it is too fast a powder for 150 grain bullets. Or any bullets for that matter.

I can't find it used with any bullet weight in Hodgdon, Speer, Hornady, Lee, or Lyman manuals.
Might want to rethink that plan.

rc

 

[ryan500]

it calls for 3031 in my Sierra manual, seems to work good. Tryed 40.4, 40.9, 41.4 and they go good no signs of pressure, next up is 41.7 and 42.2 that about all i will try. I was happy with the results of 40.9, but just wanted to try more, max is 43.9.


Checked the length for the lands and my manuals COAL is only .015" shy of the lands so i will run as is at 2.900" for the dummie round and seat the rest the same, my bullets differ about .006" is some cases

 

[rfwobbly]

Ryan -
The Russian design guns are usually "7.62" in name only. If you'll slug the barrel you'll see the bore is actually about .312" and not .308". If you'll use correct fitting bullets the accuracy will improve tremendously.

Of course with a tighter bullet in the barrel you'll have to start your loads over at the minimum load again.

 

[matrem]

I'd recommend sticking with that 2.900" max OAL.
I've yet to see a Mosin that was particular enough to show any accuracy preference in how far the bullet was from its lands.

 

[ryan500]

Sounds good guys, i'm running .311 bullets not .308 already, so we should be good to go.


Back to the range tommorow am in -24 C see if i get better results.

 

[_N4Z_]

The Sierra does list 3031 for 150 and lighter, but note that these loads are tailored for .308 rounds.

I have experimented with 3031 myself in x54r and had only mediocre results. POIs were quite high at 100 yards with the Sierra loads iirc.

Best load for me to date running 150gr rounds (both Sierra Prohunters and HornadySP), has been 46gr H4895 and an oal of around 2.86-2.87.