Calling all Straight Pull Reloaders - Bullet Inertia

gruntus · August 10, 2019

***Health Warning - All bullets/rounds referenced below have been dummies made up with no primer or propellant in the process ***

Hi All,

I have a 7.62 x 54R straight-pull Izmash rifle and I am trying to reload for it to try and get a little more accuracy than using bog-standard milsurp (which is about 1.5 to 2 MOA and is apparently the expected accuracy) and also to be able to make ammo if/when supply of factory ammo is erratic.

The key issue I have is getting the bullet to remain firmly seated in the case during cycling. It's not immediately obvious when cycling the round but the inertia of the bolt acts just like an inertia bullet puller hammer and the bullet gets pulled from the case.

The criteria I have set is to be able to cycle the bolt three times from the straight back bolt release "charge" of the round under the spring tension and for the bullet not to move "out" when simulating a worst-case scenario at the range of having a "Stop Stop Stop" or other event and hence feeling confident that the rounds can be re-chambered a couple of times without concern.

I am using new Lapua brass and have tried a few different bullet weights with and without a cannelure including crimping even using a bullet sealant to help its grip. Ideally, I want to use 150grain bullets however nothing has satisfied my criteria.

It should be noted that the 7.62 x 54R uses .311 bullets and hence bullet choices are limited. I had managed to get some .311 150gr PPU bullets (B219 heads) from the states which I was hopeful of but unfortunately despite showing a cannelure in the brochure they didn't have them when they arrived.

So the key questions are:

1) Does anyone know of a supply of milsurp/standard .311 bullets (heads) between 147 - 150 grain that have a cannelure I could try?

2) For the guys/gals that have straight pulls out there that have a heavy bolt (AK's?) have you noticed this before? Also have you been able to resolve/reduce this?

Hopefully, there are a few options out there I can try before giving up and living with factory ammo. 😢

Best regards

G ☺️ 👍

cheshirelad · August 13, 2019

I reload for 2 different AR308's and have had no problems at all.

terryh · August 13, 2019

Gruntus,

Re. Light weight bullets - you can always add a cannelure (sp?) by using one of these: https://www.buffaloarms.com/bullet-cannelure-tool-4d12000. Which are very easy to set up had one for 22 hornet.

Re. Bullets - personally i’d Look at the Lapua bullet make specifically for this round thus: https://www.lapua.com/bullets/d166/ and make sure you have a rubber butt pad 😊

The above ‘assumes’ you are playing with the Tigr version of the SVD?

always thought they’d be a fun rifle to play around with. I had a functioning Romac when I lived inn the US that used the same round, worked well with the 174g SMK normally associated with the 303.

T

gruntus · August 13, 2019

Hi Gents,

Thanks for the replies.

@ Cheshirelad - Quick question, have you ever measured your rounds with a comparator before and after having cycled through the chamber (without firing of course and done in a safe manner)? Do you crimp your rounds?

@TerryH, I didn't even know there was a tool for creating a cannelure........😳

You are certainly correct with it being a Tigr SVD. I have used the 182gr Privi factory ammo previously and it is quite "stiff" to shoot as its quite a light rifle (and yes I do have a rubber pad! 😀).

The D166 design looks right but its quite a heavy bullet at 200gr, pity they don't make a junior version.

All of the milsurp ammo is circa 150gr (just under IIRC) but has a cannelure and sealant.

Hmmmmm, I think I need to go back and review my crimping method.............

ATB

G

Andrew · August 13, 2019

I load a heap of 7.62x54R but none for a straight pull. I do load a lot of 7.5x55 fro K32 Swiss and I've never had the issues you talk of -nor have I had that issue with autoloading rifles of all makes.

I would look to your expander ball diameter. Next your brass condition (ductility) . Lastly, you do not need a cannelure to use a Lee Factory Crimp die. Get one and use it. I won't load for any cartidge without using it. Are you using small based reloading dies and FL resizing?~Andrew

gruntus · August 14, 2019

Hi Andrew,

Thanks for your info. As above its brand new Lapua brass and have tried with the Lee factory die on both cannelured and non-cannelured bullets.

If no-one has ever seen this issue it likely points to (ahem) one person............

I will revisit my crimping method and provide an update.

ATB

G

terryh · August 14, 2019

Andrew - forgot all about the Lee factory crimp die, used one on my K22 hornet to good effect.

cheshirelad · August 15, 2019

On ‎8‎/‎13‎/‎2019 at 7:26 PM, gruntus said:

@ Cheshirelad - Quick question, have you ever measured your rounds with a comparator before and after having cycled through the chamber (without firing of course and done in a safe manner)? Do you crimp your rounds?

I don't crimp my rounds, not sure anyone I know who shoots either an AR15 or an AR308 does, no I haven't measures a round having cycled it but all my ammo performs as it should, never had a problem.

deadcenter · August 15, 2019

I only shoot this round in my nagant but use the sellier and ballot 180gr bullet which has a canular. Good bullet and quite cheap. I always use the Lee factory crimp die and have never had issues with rounds in the magazine having bullets move. Not the same as the bolt slamming forward I know, but seems a solid round in my application.

gruntus · August 28, 2019

Hi All,

Quick update for completeness and anyone in the future that may come asking the same thing.

Carried out some tests with new brass full-sized with/without the button to increase neck tension and also with/without a crimp using the Lee factory crimp die to see if I could get something that worked.

The best results obtained for keeping the bullet secured in the case was full-length sizing without the button to increase neck tension and a light crimp.

The following process now successfully meets the original requirement (i.e. the bullets required to remain seated in the case after a number of harsh cycles).

I suspect case life may be short given the amount of work on the brass but I will anneal on each firing to try and prolong accordingly.

Method

1) Full-length size "new" brass with Lee die. * For some reason, the new brass comes predominantly dinged on the necks and requires FL sizing die with button to straighten them out.

2) Resize brass with the button removed thus creating additional neck tension.

3) Seat the bullet.

4) Crimp using Lee factory die.

5) Good to go!

Notes

It should be noted that the bullets do still pull out the case with inertia when slammed forward (8 to 11 thou) and then progressively move further forward out the more you do it, however, in my tests I was able to cycle the bolt "hard" five times and the bullets remained firmly in the cases which was essentially what I wanted to ensure some level of consistency but more importantly ensure safe operation with the reloads.

I also found a good article here http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm The whole article is good but the Neck Tension section reiterated my findings.

Thanks to all that commented and hope this is of help to anyone in the future. Now I just need to see if I can develop a load that it likes.

All the best. 👍

G 🙂

cheshirelad · September 1, 2019

I checked all my friends who load for straight pulls like me, particularly LMT's, AR308's and SLR's and no one crimps, I have no reason to crimp but maybe your rifle does, glad at least you found a solution.