Please, need help from military 7x57 gurus

[sghart3578]

Hello guys. I have a new project that I need some advice on. I have a BRNO VZ24 in 7x57 that I bought 15 years ago. Now that I am semi-retired I have decided to try to get it to shoot. I ordered an assortment of boolits to experiment with. While I was waiting for them to arrive I loaded some 140 gr jacketed bullets over the minimum load of H4895. These clocked at 2500 fps but accuracy was very poor.

I know these rifles have a long throat and the 140 gr bullets were about 1/4" off the lands. I measured this with a tool I kluged together. Today my cast boolits arrived, an assortment from 4 different molds. They are:
Lyman 287641
Lyman 287405
Lyman 287308
Lee 285-130-R

Using my homemade tool to measure I seated the boolits to the following OAL's. This should put each round about .015" off the lands.
Lyman 287641 3.025"
Lyman 287405 2.83"
Lyman 287308 3.014"
Lee 285-130-R 2.715" (The Lee boolit is much shorter than the rest. This depth put the boolit .2" from the lands. I can only guess that the Lee boolit was designed for more modern
rifles.)

My question is do these figures look ballpark close to you guys with experience? My load on all of the rounds is 16 gr of 2400. Any help you can give me would be appreciated. I am going to the range in a couple of days to try them out.

Thanks in advance for your time.

Please see new post.

[dromia]

I'd go for the one that best fills the throat, Loverins are good throat fillers and my Lee soupcan is large and is a good throat filler too. I'm shooting an original 1895 OVS Boer Mauser and there is no way I'd get near the lands with any boolit in that.

I'm looking forward to BC's 7mm Thor and NOE's 150 gn Loverin in 0.288" they should be good throat fillers too.

[Lefty SRH]

Im waiting for the NOE 150 also, I couldn't get the 7mm THOR to shoot though.

Like Dromia said, try and fill the throat the best you can. I've heard the 287405 is well in the mil-surp rifles. If that 287641 IS the older version that has the dirt grooves in the nose it should work well also. Which version do you have? I'm not familiar with the 287308.
Try and size them about .002" over your groove diameter.

Also, I have found that the original design weight bullet that has worked best in my mil-surp. Which is the jacketed 175gr RN and some IMR 4350.

[atr]

most certainly agrees with Lefty about the 175 gr RN jacketed using 4350....it is very accurate in my 1895
for cast the Loverin works really well and your load of 16 grains of 2400 is a good place to begin

I have used the 140 gr J in my Ruger#1 and the accuracy was very good

[Larry Gibson]

Concur on the 175 jacketed RNs for best accuracy except I load mine over 4831 to 2400 fps (wihtin SAAMI MAP for the 7x57). The lighter weight bullets of .284 diameter many times do not shoot the best in milsurp 7x57. My M9 is an exception to the rule with the barrel pristine at .288 groove diameter and .275 bore. That deep rifling gets a good grab on the undersize .284 commercial bullets. I also find the FB'd jacketed shoot better than BTs. Additionally I use 4895 and Varget for top end loads (I measure the psi and stay within the SAAMI MAP) so the bullets may obturate and seal the bore.

For cast you should really slug the barrel as you'll probably find the groove diameter at .287+. and more likely .288+. As mentioned you'll want to size those to fit the long throat. I got a custom .288 H die from Bullshop for a reasonable price as my older RCBS Lovern style mould drops them at .287 - .288. I get excellent accuracy with that bullet in the 1900 fps range with medium burning powders, particularly 4895. I have used several other moulds and find the Loverin style Lymans (287405 any 287448) and the older RCBS 28-160-FN (Loverin style shown in photo) shoot the best when left as cast at .287 - .288 in milsurp barrels.

The 287405s you have will probably do the best if they are at .287 - .288. The 287308 will do ok too if sized at .287 - .288 and the nose is not too small. I suggest a medium burning powder, a dacron filler and keep the velocities in the 1800 -1900 fps range.

Larry Gibson

[Smokepole50]

Larry, Have you ever shot cast boolits in a 1912 Chilean? I did a chamber cast on mine and it has no throat, maybe a 1/16" at most then the rifling starts.

[Lefty SRH]

Larry, Have you ever shot cast boolits in a 1912 Chilean? I did a chamber cast on mine and it has no throat, maybe a 1/16" at most then the rifling starts.

WOW, now that is SHORT! I thought my Ruger modern commercial was short DAMN! Your Chiliean has mine beat!

[UBER7MM]

If you have an original 7x57 military barrel, it'll have a tight twist, 1:877 or so, I believe. It was designed for a 173 grain "j-word", so I'd start with the heavier and longer boolit in your list. For example, I've had success with the 287461 under 4895 and 4064 in a 1:9.5 twist barrel. This corresponds with Larry's suggestion of a medium rate burning powder. The Lyman handbook doesn't have a listing for this load so you may need to experiment or find another published resource to base your pet load on. I like to touch the nose into the lands, for an OAL of 3.065". Your results may vary.
.
.
I hope this helps,

[sghart3578]

Thank you UBER7MM,
That is the info I was looking for.

I want to thank every one who has answered, their expertise is appreciated. And it could be that I didn't phrase my question well. What I wanted to know was if the OAL's of my handloads were close to what other guys with these rifles had found. You answered that and I thank you.

Steve

[Larry Gibson]

Larry, Have you ever shot cast boolits in a 1912 Chilean? I did a chamber cast on mine and it has no throat, maybe a 1/16" at most then the rifling starts.

That has got to be a real anomoly.....never saw any milsurp 7x57 barrel with that short a throat!

Larry Gibson

[dromia]

I couldn't get the 7mm THOR to shoot though.



I'd like the chance to find out!!

Still no sign of the mould and no updates from BC either, they rate along side Lee with me now in customer care.

Your the customer we don't care.

[UBER7MM]

sghart3578,

BTW: My jacketed pet load is 154 grain Hornady SP #2830 jackets loads measure 3.064". That's .030" back from the from the lands. I use the minimum listed load of IMR-4320.

Good, safe shooting and welcome to the forum,

[7s&8s]

I have had the best luck with 7mm milsurps using a lapped RCBS 168 gr that drops at .288-289 range, sized to .288 over 2400 or 4895 powder. Including Chilean 1912.

Best Regards,
Tom

[Jeffreytooker]

7x57 surp ammo is .286". Old military 7MM bores are larger than the now standard .284" for 7MM. That is why Jword .284" bullets do not do well. Boolits are definitely more better in this case. I have a .287" mould that I have yet to use. If I do I will shoot as cast first.

Jeffrey

[Larry Gibson]

.286 - .288 was the European standard for the 7mm groove diameter. The British standard was .284 for their .275s and .280s (7mm's). Guess which one we adopted?

Larry Gibson

[sghart3578]

First, I want to thank everyone who replied to my questions. Your info was a great help. I finally got a chance to shoot my test rounds and compare results. I was pleasantly surprised by all 4 of the bullets tested, even the ones from the Lee mold. Before the Lee fans object let me clarify. No one is a bigger Lee fan than me, a look at my reloading room with 4 Lee machines will attest to that. I was surprised by the performance of the Lee bullet only because I was trying to get the bullets seated out to touch the lands. The three Lyman bullets were long enough but the Lee design was too short. However the Lee design shot very well. Before the test my money was on the Lyman 287308 based on threads that I had read in the past. But the winner was the Lyman 287641, barely. All groups were close. This is a great result for me because the 287641 mold is still available and the 287308 is apparently out of production.

I also got ahold of 20 Hornady 175gr jacketed bullets and loaded them with a 60% load of H4895. I seated them .010" off the lands. These were an absolute tackdriver. Almost no recoil and three bullets into one hole at 40 yards. Thanks Uber7MM.

I did not chrono any of the loads because of time constraints but that will happen next week. I will post those results if you guys are interested.

Thanks again.