mauser "truck gun" bullet jump issues

[oldscot3]

I've had for years, a little mauser truck gun that has never delivered accuracy any better than a typical AK 47, which is to say about 4 moa +/-.

Now part of the issue is it's equipped with a 2 3/4 x german 3 post scout scope which is very good for it's intended use, but not so good for accuracy testing. I have however, used it on a 6.5 swede with good results so I never believed it was the main problem.

Recently, the bulb slowly came on in my head and I decided to do a thorough investigation. What I found was a tremendously long leade. How I missed it before is beyond me, I should have known it before I ever had the smith screw the barrel on my action, nevertheless it got by me.

Measuring from a point where a round nose Hornady bullet engages the rifling, then to the bolt face, I have 3.32". That meant that a lot of the lighter weight 140 grain bullets I tried were completely out of the case before they entered the rifling. Not good for accuracy I can tell you from experience.

The load I've settled on now uses a Hornady 154 grain round nose and it does just manage to reach the rifling before the base clears the case. Accuracy is much improved and I now have a truck gun that's more useful to me.

I guess the reason for my post is just cautionary and perhaps unneccesary for most of the members here, however, for others maybe it can be a reminder to do all your due diligence before investing a lot of time and money on a project gun. Had I done so, I could have saved myself a whole bunch of bullets and powder.

[tobnpr]

I should have known it before I ever had the smith screw the barrel on my action, nevertheless it got by me.

Background?
This was a military take-off that you instructed he install, without inspection?

[oldscot3]

No, this was a military "new in the white" replacement, which was inspected by myself and a gunsmith but apparently neither of us gave adequate consideration to the amount leade. As you probably know, early military barrels often came cut with long leades to accommodate long, heavy for caliber round nose bullets.

I just totally let that go by when I was trying to get lighter, spitzer bullets to shoot out of that gun.

[T. O'Heir]

Accuracy issues(that I don't think you have) with a "military "new in the white" replacement" barrel on a milsurp rifle are kind of normal. Military barrels are not made for great tack driving accuracy. And a consistent 4" at 100 yards isn't horrible. That's what is meant by 'minute of deer'.
Kind of doubt worrying about the off-the-lands distance will make any difference either. That's a load tweaking technique fiddled with after you have worked up the load. Sounds like you're not reloading.
Anyway, the 156 grain RN was only used until 1940. The Swedes changed to a 140 grain spitzer then. How old is the little Mauser truck gun? The rifling twist may be for the 156 or the 140. 1 in 7.87" for the 156.

[oldscot3]

Oh yes, I am reloading. I have the remains of two old boxes of Hornady 154 gr. RN bullets that I'm using. I worked up to a max load of RL 19 and it seems I now have something a little better than "minute of deer".

Keeping in mind that a 2 3/4 x with a german 3p reticle is not a good target scope, I fired 11 shots at a 2" square 100 yards away. My extreme spread was 3 inches but 7 of the eleven shots grouped just under 1 3/8" and they were nicely centered on the target.

I think that's best I can do with a scout scope and I suspect it indicates that my little gun is capable of 1 1/2", or better, at 100 with this load.

BTW, this rifle is a 7mm mauser not a 6.5 swede. I may have confused the issued by saying I had previously used the scope on a 6.5 x 55. I also neglected to mention the caliber in my first post. Sorry for that.

[T. O'Heir]

The 7mm Mauser military round started out with a 173 grain bullet. Then a 140ish then to a 162. 175 being close. It's also one of the really under rated cartridges there is. Used by W.D.M. Bell for hunting elephants 100 plus years ago.
Anyway, consistency is what's important.

[oldscot3]

Agreed.

I only wished to use lighter bullets to pick up a little velocity given my barrel's 19 1/2" length. I think it's safe to say however, I really don't need any more velocity, as it appears that my eyesight and ability to aim this scope is going to limit my range to under 200 yards for sure.

I'm going to settle on this load until I run out bullets, which should be awhile since I won't be needing to spend many of them on paper anymore.

[oldscot3]

oops, sorry. miscue with picture from my phone experiment.

[Paul B.]

Sometimes that long leade is not as much of a problem as some think it is. I have three rifles chambered to the 7x57 and two for sure have that long leade meant for 175 gr. bullets. One, a Ruger #1A is MOA with everything I've run through it and a Winchester M70 Featherweight is MOA to sub MOA depending on what weight bullet I'm shooting. The third rifle is a custom built on an M 98 FN Mauser action and I'm not quite sure what the throat and leade are on that barrel. According to the gunsmith it is the standard SAAMI chambering and leade but that rifle shows high pressure very rapidly. It does however shoot very accurately with Winchester factory 145 gr. Power Points. (.50" to .75" depending on how well I'm shooting that day.)

A load that has proven very accurate in all three rifles is winchester brass and standard primer, 47.0 gr. of Re17 and the 150 gr. Nosler Partition. Velocity from the FWT runs right at 2700 FPS.

Paul B.

[oldscot3]

Totally agree; you really don't know what a given rifle is going to "like" until you've tried a number of different loads. Many times I've seen cases where the conventional wisdom went in the trash can.

In this case however, I've tried a number of handloaded bullets from Nosler, Speer, Hornady, Sierra, as well as several different factory loads both mil surp and USA manufactured loads for hunting. The little rifle has pretty consistently shot the longer, heavier bullets best.

I guess the wild card that was throwing me though, was the scope. As noted, it's only 2 3/4 x and it has broad reticle bars of the german 3 post pattern. While it's much easier on my aging eyes to sight than irons, it's still hard for me to see very small shot-to-shot sighting variations at 100 yards.

I think all these years I was the primary culprit, guilty of throwing off some shots and ending up with head scratching results.

[ThomasT]

I have a custom 8mm Mauser with the barrel turned down and the steps removed. It also has a long lead and shoots better with Sierra 175gr Pro Hunters or a few of the old Hornady 180gr round nose bullets I have. Those are the heaviest bullets I have in that caliber. I would like some 190s to try.

Too bad RN bullets aren't more common. I think its easier to get good accuracy with them than with Spitzers sometimes. At least they seem to give good accuracy with about any suitable powder you try. They just don't look very sexy and most turn their noses up at them.

I do have a stock of the Remington 185 SP and those do shoot good in my gun.

[oldscot3]

Yep, I have a partial box of Sierra 160 gr. RN bullets and a full box of Hornady 154 gr. RN bullets. Both discontinued, once they're gone about all I can do hope I might see some at a gun show.

To be honest though, they're probably enough. This rifle's main job is to ride around in the pickup and won't be shot very often once it's dialed in. It never goes to a blind and so far the only thing game its taken is one little sow pig.

[Scorch]

the lighter weight 140 grain bullets

now uses a Hornady 154 grain round nose

From the bullet weights you quote, I am going to assume you have a 7X57 you are trying to get familiar with. And yes, they have long throats.

Everybody wants to seat bullets against the rifling. You have to play with different seating depths instead of just cramming the bullet into the rifling. Find the "sweet spot" by loading to slightly different OAL (.010" difference in OAL), then see where that spot is. For my Ruger 77 in 7X57, it was right around .060" of bullet jump. And if you do decide to just cram the bullets into the rifling, flat based bullets have longer bearing surfaces than boat tails.

[oldscot3]

Well, yes and no.

Yes, 7 x57 with a 19 1/2" military carbine barrel.

No, I'm not interested in cramming the bullet into the rifling. What I discovered though, was quite a long leade, so much that a 145 gr. Speer flat base SP actually clears the case before it engages the rifling. After much experimenting, I've given up on bullets in that weight range, seated at any length.

I think it's all sorted out now; I'm using two old boxes of discontinued round nose bullets from Sierra and Hornady in 160 and 154 grain weights. They're providing good accuracy, with my primary challenge being my scope now, not my loads.

Thanks for the reminder though, your procedure for finding optimum oal works for most rifles.

[std7mag]

Weatherby's traditionally have a long lead.
Same with 284 Win, 30-30, etc.
Most of the semi-autos, pump action, lever action, and break open action rifles are known to have long leads.

[hooligan1]

I have a 1908 in 7 mm mauser that really likes 175 grn Sierra Gameking btsp's and 7828, and the scout scope I put on it helps me a ton.
It has the 29.5 in barrel on it and that makes a difference, velocity's can't be very high, and it barely nudges me at the butt.
Shoots less than moa at 100 yds and I'm totally tickled about that..

[oldscot3]

Correction; I have been saying the Sierra round nose bullets that I have are 160 grain, not so, they are 170 grain.

At any rate, it is still correct that they, and the Hornady 154 grain round nose bullets, are discontinued.

[bamaranger]

A goodly percentage of most of the rifles I own shoot better with the COAL beyond SAAMI spec. Two prime offenders are a new Savage Hog in .308, and a used Mark X Minimauser in .223. The Mini's bigger brother, a Mark X in 30-06 is about as bad.

As a contrast, a twenty yr old Rem 700 ADL in .270, bought new, which has a accurate but copper fouling prone bore, seems to care very little about seating depth, shooting nearly every bullet weight, and brand of slug, to about the same useful POA. I've never measured, but the Sierra 110gr Pro Hunters are way short of the rifling, but they still plunk in there with the the heavier 130 and 150 gr slugs, just a very forgiving rifle. As long as you degunk it about every 20-25 shots.

Fun part of the hobby, figuring out what makes them tick.

[fourbore]

I've had for years, a little mauser truck gun that has never delivered accuracy any better than a typical AK 47, which is to say about 4 moa +/-.

Now part of the issue is it's equipped with a 2 3/4 x german 3 post scout scope which is very good for it's intended use, but not so good for accuracy testing. I have however, used it on a 6.5 swede with good results so I never believed it was the main problem.

Recently, the bulb slowly came on in my head and I decided to do a thorough investigation. What I found was a tremendously long leade. How I missed it before is beyond me, I should have known it before I ever had the smith screw the barrel on my action, nevertheless it got by me.

Measuring from a point where a round nose Hornady bullet engages the rifling, then to the bolt face, I have 3.32". That meant that a lot of the lighter weight 140 grain bullets I tried were completely out of the case before they entered the rifling. Not good for accuracy I can tell you from experience.

The load I've settled on now uses a Hornady 154 grain round nose and it does just manage to reach the rifling before the base clears the case. Accuracy is much improved and I now have a truck gun that's more useful to me.

I guess the reason for my post is just cautionary and perhaps unnecessary for most of the members here, however, for others maybe it can be a reminder to do all your due diligence before investing a lot of time and money on a project gun. Had I done so, I could have saved myself a whole bunch of bullets and powder.

This is a informative and spot on post.

[gwpercle]

Back in the 1960's when Military 8x57 Mausers were common we got good accuracy with Hornady 170 grain RN or their 195 grain SP those long bullets took up some of that extra throat .

In the surplus military 7x57 rifle I still have the Hornady 154 grain RN was the shortest that would shoot well and the 175 grain RN was the most accurate .

I guess all my days spent with these long throated military rifles have caused me to prefer long heavy for caliber projectiles....
So if you ever get an old military bolt gun from WWII era check the leade and don't be afraid to try long heavy projectiles, moving at moderate velocities they can deadly on game. That little 7x57 model 95 Mauser I have , with the 154 grain RN load, has dropped several deer with one shot...it just works.
Unfortunately , Hornady has discontinued the 154 gr. RN...but Speer makes a 160 grain that will do.
Gary
Gary