P95 Oversized Bore Boolit and Bullet Advice

[Sturmcrow]

The previous post on the oversized bore of the P95 got me wondering about my new purchase. I just slugged my P95 barrel today and came up with 0.3565 for the groove diameter. Since I'm starting from scratch with reloading components for 9mm, I'm thinking maybe I should go with slightly larger bullets than standard.

0.358 seems to make sense for cast, though that's 1.5 thousandth's instead of the recommended 1.0 thousandths over groove diameter. Any problem with that?

For jacketed, I'm thinking about returning the .355 bullets I've got and picking up some .357. This is 0.5 thou over groove diameter. Anybody think that will be a problem? I don't think I've seen .356 jacketed bullets anywhere.

This gun is intended for plinking and working on my technique. I despise inaccurate firearms though, so anything simple like bullet size I can do to bring group sizes down is a good thing. I've got a 10MM for more serious work, which slugged out to exactly 0.4000, lucky me. Yes, that is an aftermarket barrel.

Edit: I guess there are a couple options for .356 jacketed at Midway. That HAP is a decent bullet too, from my experience. Would .356 be better/safer for my gun?

[theperfessor]

Going over by 0.0015" with cast shouldn't be a problem, with the following caveat: If you have a tight chamber then you might have a problems chambering the loaded round. Depends on how thick your brass is and how deeply into your case you seat your bullet. This is one case where a bevel base bullet might cause less problems, especially with heavier (147 gr) bullets.

[anachronism]

.358 is fine. You're in good shape there. For jacketed bullets, you can always experiment & determine what the gun likes best. P95s are sturdy, reliable guns, but I wouldn't expect target grade accuracy from one.

[Sturmcrow]

.358 is fine. You're in good shape there. For jacketed bullets, you can always experiment & determine what the gun likes best. P95s are sturdy, reliable guns, but I wouldn't expect target grade accuracy from one.

I'm not expecting much. I do think it's interesting how the reviews for the .356 HAP bullet at Midway comment on how it is the most accurate bullet for their gun... which probably has an oversize barrel.

I think you're right. 100 of the HAP's and 100 .357 XTP's should be a decent sample to check accuracy and pressure. For the sake of science, I suppose I should also try .357 and .358 cast boolits too.

Is there any relationship between cast boolit hardness and recommended size? I.e., should I use bigger or smaller sized for hardcast vs. air-cooled wheelweight?

[Sturmcrow]

Going over by 0.0015" with cast shouldn't be a problem, with the following caveat: If you have a tight chamber then you might have a problems chambering the loaded round. Depends on how thick your brass is and how deeply into your case you seat your bullet. This is one case where a bevel base bullet might cause less problems, especially with heavier (147 gr) bullets.

I hadn't thought of that. Perhaps I should try slugging the chamber. I did notice that the throat is very rough. I can see concentric tools marks, as if the cutter had a chip out of it. I may have to try fire-lapping, or a call to Ruger to see if this is normal.

[sagacious]

0.358 seems to make sense for cast, though that's 1.5 thousandth's instead of the recommended 1.0 thousandths over groove diameter. Any problem with that?

Nope, no safety problem with that. 5 ten-thousandths increase in diamter is not gonna get you into trouble on it's own.

For jacketed, I'm thinking about returning the .355 bullets I've got and picking up some .357. This is 0.5 thou over groove diameter. Anybody think that will be a problem?

Nope, no safety problem with that... as long as the loaded rounds will easily chamber without resistance. If you use mixed headstamp brass, be aware that some brands of brass may be much thicker than others, and this may sometimes lead to chambering difficulties if you use a bullet larger that .355". Not a probability, but be aware that it is a possibility.

You may be counting your chickens before they're hatched. .355" jacketed bullets may actually give good accuracy in your gun. One needs to test these things to be sure. Nobody here can assure you of accuracy with any combination of components or combination of dimensions-- you have to test them for yourself in your gun, and with your reloading technique. .357" plated bullets can be easily resized to .3565" in a simple push-through LEE sizer, or a conventional wax-luber like the RCBS lubrisizer (with no lube pressure). This is an excellent way to achieve tight neck tension with short bullets in calibers such as 9mm or the 357Sig that has a very short neck, or to size to a specific bore diameter.

Even still, as long as they can chamber easily and without sticking, and as long as the bullet ogive is not jammed into the throat/rifling, appropriate-weight .357" jacketed bullets would be safe to use in your .3565" bore. 5 ten-thousandths over bore diameter is not a safety issue here either.

Would .356 be better/safer for my gun?

Better? There is achance that .356" may be more accurate than a .355" jacketed bullet. Safer? No, that 1 thousandth is not likely to convey any safety benefit in a jacketed bullet in 9mm Luger caliber. But if I had to choose between .355" and .356" jacketed for that gun, I'd easily choose .356", on the basis of measured bore size alone.

Hope this helps, good shooting!

[Sturmcrow]

Thanks for all the advice. I got some .355" 147gr jacketed and 125gr plated bullets loaded up and some .357 125gr jacketed and .358 125gr cast bullets as well.

Now I just need a slow day at work and a break in the weather to get out and see how the accuracy looks between these. I tried to keep everything fairly consistent with the same load of Accurate #7 under all the 125 gr bullets and a reduced load under the 147gr.

This is of course only ballpark. I figure I'll see which rounds look fairly accurate, compare that with the cost of the projectiles to make a decision, and then worry about which load and OAL works best.

[lwknight]

All I can tell you is that .355 bullets are not accurate worth pooopooo in my P-95.
The barrel support and battery lock are rock solid so I believe that the overbore is the culprit.
I did shoot a few cast .3565 boolits and still got some leading that cleaned up easily.
They were more accurate and I did not shoot a lot since I expected some leading.

I will get my chance to try some .358 boolits soon. Looking forward to it.

[lwknight]

I got a P-95 barrel off gunbroker for $22.00 and it slugged out at exactly .355
Now I can't wait to get to the range.