Throat tighter than rest of barrel on Walther PPQ

[DougGuy]

I wouldn't give up on it just yet. You were shooting water dropped coww, probably got a BHN of no less than 18, likely closer to 22. What you would need to overcome this choke, is an alloy that is malleable and soft enough to obturate to the bore after it clears the choke. I would try air cooled coww, and if it leads then mix some soww or pure lead with it, and use some soft lube too.

My SBH took an immediate liking to 50/50+2% coww/pure lead/2% tin with Felix lube and it performs well with other soft lubes. I can scratch the boolits with a thumbnail, and I run them right at 1180 ~ 1200 fps with ZERO leading and great groups. They ARE the gas checked Lee RF boolits, and I admit I am shooting in a revolver with reamed and honed throats, into a nicely cut forcing cone, but the results are very gratifying.

With only .0003" of constriction, a soft enough alloy and soft lube would obturate and seal in the bore, but to shoot a soft enough load to do this, likely it won't be a max velocity load. Maybe 1200fps or even slower.

The rifling in your bore is very proud, it reminds me of looking down a SBH bore. I think there is good reason to try with softer alloy and soft lube and see if you can't hit on a combo that the barrel likes. Might not hit it dead on first time out, it may take 2 or 3 tries but you will get to the point that you look in the barrel and notice something got better. Something's different. It's not leading like it usually does, and from there you should make small changes, one at a time, and see if you can't dial in a combo that works.

[Handloader109]

I'll chime in here one more time, and to agree with DougGuy. I'm shooting a powdercoated bullet try my PPQ. In fact, Several, 95 gr NOE ranchdog, Lee 124 and 125gr. If I shot plain lubed with Alox, it would lead, PC didn't. Now I sized mine down to .356. Accurate is not as good as jbullets, I'm expecting they should maybe be .357, but haven't spent the few $ on sizing die to test. My lead is soft, has been wheelweights and range scrap. Doesn't seem to matter once powder coated. And I'm just plinking. If it were me and I wanted to keep gun, I'd try powder coating and size down......

[GaryN]

I would also keep trying. As above use a softer alloy. Keep in mind that the 9mm can be difficult to load for with cast because it is so easy to decrease the size of the boolit when loading with soft cast boolits. There is a good sticky about loading cast in a 9mm. It addresses a lot of the problems inherent in making a pistol shoot cast. It was posted by Mtgun44. Here it is:
http://castboolits.gunloads.com/show...s-in-a-new-9mm

[gloob]

I am not sure if lapping the bore is a good idea on a tennifer treated barrel, but that wouldn't stop me from finding out for myself. I'd size 11 BHN bullets to w/e is smaller than the freebore and larger than the constriction and mix some 400 grit abrasive into my tumble lube, then fire them over a sub-minimum starting charge for the bullet weight, aiming for 600 fps.

I'd bring a jag with a tight patch to clean out the bore every 4 shots and to feel for the constriction. When I can't feel it, I'd shoot a couple more, then slug the gun when I got home. Final polish with a jag and patch and some fine polish, and then see what happens.

[Geezer in NH]

I'd like to know how a button rifled barrel gets a tapered rifling like that? Just on the chamber end, sounds more like Crappy CS to me.

I have been a gunsmith, dealer manufacturer, sold over 100,000 barrels and cannot figure out how?

Pulling a button through a short piece of stock will not do it. Pulling a button through a longer piece and then cutting barrel lengths from it won't either.

[gpidaho]

Not to beat it to death, but try running some powder coated boolits through it. The PPQ I shoot just loves the Lee 356-124 powder coated and sized .358. NO leading after 300+ rounds down range. Good luck GP

[DougGuy]

I'd like to know how a button rifled barrel gets a tapered rifling like that? Just on the chamber end, sounds more like Crappy CS to me.

I have been a gunsmith, dealer manufacturer, sold over 100,000 barrels and cannot figure out how?

Pulling a button through a short piece of stock will not do it. Pulling a button through a longer piece and then cutting barrel lengths from it won't either.

This is a Tenifer treated barrel. It gets HOT when they heat treat it. Over 1,100°F in the salt bath. The breech is 3-4x thicker than the rest of the barrel. When metal cools it contracts. The thicker area ahead of the chamber contracted enough to squeeze the finished bore down .0003" as it cooled from heat treating.


http://castboolits.gunloads.com/show...=1#post3262023

[Char-Gar]

Not wanting to ruin your tooling cutting super hard stuff reminds me of the time I tried to get Herretts make me a pair of handgun stocks from Micarta. They said they would do if for an extra $200.00 to pay for the cutter bits that would be destroyed in the process. I decided that wood was plenty good. -

[gloob]

This is a Tenifer treated barrel. It gets HOT when they heat treat it. Over 1,100°F in the salt bath. The breech is 3-4x thicker than the rest of the barrel. When metal cools it contracts. The thicker area ahead of the chamber contracted enough to squeeze the finished bore down .0003" as it cooled from heat treating.

I understand conventional kinds of heat treating can do this, too, to some degree. I've heard that touted as one of the benefits of a bull barrel, anyway. No taper, no inadvertent "reverse choke."

With mandrel forging it should be possible to shape the mandrel to account for this specific problem. I wonder if Glock and HK adjust for this shrinkage.