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Discussion Starter #1
Hello all,

I recently bought a spanish mauser in 7X57mm. It's in kinda rough shape, the stock has been cut down and the barrel shortened to about 20" the barrel is also fairly rough with rust and pits. It has a great trigger though, especially for a 2 stage military, probably around 3-4lbs. I got it real cheap with the idea of putting an Adams & Bennett bbl on it from midway (in the original 7X57 cal), since the action and bottom metal are in decent salvagable condition. Kinda want a lightweight knockaround rifle, something to plink with and maybe shoot a deer, plus I've never hada 7mm before.

Anyway, I wanted to put it on paper before the rebarrel as I have had a few pitted barrels still shot OK. Not this one, at least not at first, I was getting 5 shot 50yd groups of 6-8"! First I thought the 140gr bullet was the problem, so I tried a 175gr Speer and a 150gr Sierra HPBTM. No dice, same result. I tried a few different powders, partial sizing, etc. I even cleaned up the crown myself with grinding compound on a tapered grinding stone to no avail. I was about to give up and go ahead with the rebarrel. Then the other night I was thumbing through an old Handloader magazine when I ran across a short piece on using poly shot buffer with cast bullets in a rough barrel. The author said it made a vast improvement, but couldn't explain why. I was skeptical, but since I had some buffer on hand for shotshells I thought I'd give it a whirl.

I loaded up some Sierra 150gr HPBTM bullets with my normal powder charge reduced to a grain under starting. I then (per the article in Handloader) filled the airspace in the case with the shot buffer. I actually filled the case to the top of the case mouth then let the bullet compress it somewhat. I fired the loads today. To say that I was impressed would be an understatement! 5 shot 50yd groups immediately shrank to 2-2.5"! This from a less than steady rest in a bit of a breeze. I don't know how it works, I just know that it does. At least now I can try to tweak the load to get maybe 2 MOA, which I'll live with through the summer and rebarrel in the winter.

Sorry for being long winded, just wanted to let everyone know what I found and maybe get some imput on other ideas for helping a rough barrel. I may try fire lapping as I plan to try some cast bullets in this gun. Any ideas?

SSB
 

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Plastic Shot Buffer

I have read several posts regarding using the shot buffer, and have tried it myself in my 45 LC after reading the same article in Handloader. I had good luck with barrel leading and load consistency.

What I have found out after reading many posts on Shooters.Com regarding this practice is that the shot buffer tends to become solid-like when it sits in the case under compression. You then get a nice plug in the case (bottle neck cases only) when you fire it months later. I don't think this is a good thing. I have not experienced it myself, but I don't want to either.

I would suggest that you shoot up everything you load with buffers within a couple of weeks to avoid the possibility.

5 Shot
 

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Singleshot,

Before doing anything else, try loading some 175 gr. RN bullets. I am partial to Hornady for this cartridge.

The 7x57 guns have a quick twist around 8.5". I have had only one of the Spanish guns, but the interior of the barrel looked like it should be pulled and used for a jack handle or tent stake. I don't recall the specifics of the load since this was about 35 yrs ago, but I do remember how it shot! With the military barrel cut to resemble a Mannlicher, even including the front barrel band from the original stock before shortening, this little gun shot right around 1"-1 1/4" with regularity.

Try shooting it with bullets that are correct for the twist and long throat and I think you'll be surprised how well it will do. Who knows, you might just forget about re-barrelling.
 

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Discussion Starter #4
update

Gentlemen,

Here's a bit of an update on the buffered loads. I tweaked the 150gr HPBTM loads and got them to shoot into 1" for 3 shots at 50 yards regularly. This is the 2 MOA I was looking for so I'm satisfied with it. Unfortunately, I ran out of these Sierra bullets and I had already bought the last box at my local store. They've ordered more for me.

Now I'm trying cast bullets in the rifle. Bought a Lyman #284308 mold last weekend at the gunshow, the bullets come out weighing 171grs with my alloy. First groups weren't too impressive and there was quite a bit of leading, so now I'm gonna change a few things and see what happens. If I can minimize the leading (may not be possible with a pitted bore) and get 3 MOA with these bullets I think it'll be worth it. I'm just gonna use these loads to plink with and shoot a few groundhogs. I'll keep you guys updated.

SSB
 

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Singleshotbuff,

I suspect that your rifle may have an oversized bore, has a washed out throat and, or, is pretty rough as you have alluded to.

The way that the shot buffer works in these situations is that it keeps the powder gases behind the bullet allowing it to traverse the length of the barrel unaffected by any powder gas that could otherwise get by, hurting accuracy.

I have had several successes using shot buffer in oversized barrels and have had very good results using it.

John
 
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