Load Check 7.62x39

[tango2echo]

From Lyman 49:
123gr jsp
H-335
Start 30.5gr/2085
Max 34.5gr/2363
2.2 oal

Speer #14 shows 29.5gr Start and 31.5 Max

I started at 30.5gr and have worked up to 33.0 in .5gr increments. No signs of pressure and very good accuracy. However, I am getting surprisingly fast chronograph readings. Lyman 49 shows 2363fps with the max load of 34.5gr from a 20" UR barrel. I'm getting 2560fps from a 18" barrel with only 33.0gr! The load has been double and triple checked. The scales are right, and I've shot it over two chronographs. (The starting load of 30.5gr showed 2280fps over the chrony)

Here's the data: 2560m, 18sd, 34es from the chrony
Remington small primer pocket 1x fired brass
CCI small rifle primer
Sierra 125gr .308 jsp
H-335
COL 2.19
.040 off lands
light taper crimp

1) Would you continue to work this load up? Other than abnormally high velocity I have zero pressure signs. The brass isn't even stretching enough to require trimming after several reloads. Accuracy has improved with higher powder charges and I would like to work up safely.

2)I have some doubts about even being able to fit 34.5gr of H-335 powder in a X39 case. I loaded a small batch at 33.5gr and it is compressed lightly (stll unfired). I have measured volume of my Remington cases, Winchester cases, and Federal cases and the Winchesters hold 35.3grs flush to the case mouth when trimmed to 1.518. The others hold less. How "compressable" is H-335?

The rifle is a modified Mini-30 with the factory 18" tube .310 bore, AS tunable gas block set to drop the brass at my feet, XHeavy recoil spring, XHeavy hammer spring, 2.5lb trigger job, buffer, Hogue OM stock that has been bedded with pins added. It chronograghs normally with factory ammo and other reloads.

 

[Remo-99]

http://data.hodgdon.com/main_menu.asp

125 GR. SPR SP Hodgdon H335 .311" 2.150" 30.0 2219 35,400 CUP 31.5 2408 40,900 CUP

 

[armoredman]

Best I got with H335, was with a 30.1 grain load, COAL 2.17 under a 123grain SP, hotter loads in my vz-58 did not produce better results. I use AA#1680 almost exclusively now.

 

[tango2echo]

http://data.hodgdon.com/main_menu.asp

125 GR. SPR SP Hodgdon H335 .311" 2.150" 30.0 2219 35,400 CUP 31.5 2408 40,900 CUP

That data is for .311 bullets in a .311 bore. I am not sure is equates to .308 bullets in a .310 bore. Hodgdon's data for 7.62x39 seems off to me.

Best I got with H335, was with a 30.1 grain load, COAL 2.17 under a 123grain SP, hotter loads in my vz-58 did not produce better results. I use AA#1680 almost exclusively now.

I cannot get AA1680 locally and can't justify ordering it for the hazmat charge as I would never use enough of it to break even. Next big order I will get some though. I have TONS of H335 though.

There seems to be a 15% varience in data for 7.62x39 with H335. Hodgdon's max load is the starting load in other manuals.

t2e

 

[HOWARD J]

E-mail I received from Ruger on 6-15-10
The first production of Mini 30 had a bore of 308/309
310/311 bore size was started in 1990.
It is ok to shoot 311 bullets in 308 bores-- if you are using factory ammo ( remember they have lawyers)

 

[tango2echo]

E-mail I received from Ruger on 6-15-10
The first production of Mini 30 had a bore of 308/309
310/311 bore size was started in 1990.
It is ok to shoot 311 bullets in 308 bores-- if you are using factory ammo ( remember they have lawyers)

That is funny. I've contacted Ruger a number of times about issues with various Mini-30s and I've always been told not to shoot .311's in them. It has been so confusing as to which production runs have which bores that I just slug all of mine now to determine bore diameter. Further, Ruger built both bores simultaneously for a period of time in the 1990's with the tighter bores going to target versions of the Mini. I can tell you from personal experience that Ruger doesn't know what they built and when they built it with regards to the Mini-30's bore diameter. They have told me on more than one occasion that a certain serial number Mini had a certain diameter bore and when slugged the bore measured differently. I've shot .311 bullets out of .308 bore Mini's but the accuracy has been horrid and I have had pressure signs with even factory ammo.

None of this tells us why I am getting much high velocity or why the load data varies so much though.

t2e

 

[steve4102]

Ruger built both bores simultaneously for a period of time in the 1990's with the tighter bores going to target versions of the Mini.

Ruger built a "target" version 7.62x39 Mini? Tell me more.

I've contacted Ruger a number of times about issues with various Mini-30s and I've always been told not to shoot .311's in them.

My guess it that is because most x39 ammo is .310 and not .311.

 

[HOWARD J]

My 25 year old Hornady 110gr 308's are actually 307.
My 25 year olr hornady 123 gr 311's are actually 310
My Chinese banned 7.62 x 39 are 310
My 25 year old Korean factory ammo are 309...........
This cal. is all over the place----I load it all up & shoot it in my so called 308 mini-30--
It has been shooting since late 1985--- It will outlast me by a bunch !!!!!!!!!!!!!!!!!!!!