10mm and KKM barrels with hardcast

[wk5h]

I've been reloading for my 10mm for several years now, only using plated, and am having great results and tons of fun.

I got a box of 200gn TC bullets the other day, and when trying to seat them at normal 1.250-1.260" lengths, the shoulder of the bullet scrapes the inside of the throat on my KKM barrel. In order to get the bullet to seat correctly, I have to seat the bullet to an OAL of 1.216", which sounds WAY deep to me.
A bit of googling and some talking to some guys who shoot cast, pretty much all have come to the conclusion that the throat of my barrel is too narrow for the .4015 bullets I'm trying to use, and one of the options would be to ream the throat.
My question is, this is my only barrel currently, and I have several loads worked for plated bullets that perform extremely well. If I ream out the only barrel I have for 1-2 bullets, it seems like a daft thing to do when primarily I'll be shooting my other jacketed loads, and only shooting my cast loads for occasional hunts.

Would a better thing to do, be to buy a 2nd barrel, ream the throat to accommodate the cast loads, and use that barrel only for cast loads?

FYI, this is what it looks like after I forcefully fully seat a round with 1.260" COAL into the chamber, and pull it back out. Lots of scraping on the shoulder of the bullet
179043

[Dan Cash]

Seat the bullet in the case so that it is not engaged by the chamber and reduce powder charge to accommodate the deeper seating. TC bullets don't usually do well if seated with any bullet body extending beyond the case mouth.

[wk5h]

Dan, here's the pic of it loaded to the shoulder, which again, puts the COAL to 1.216". What's your opinion?

179052

[DougGuy]

That barrel needs throating, here is what needs to be done to it, this is either a LW or KKM 10mm after throating:

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/Glock%20Throating/Glock19-640_zpsv5rzqop5.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/Glock%20Throating/Glock19-640_zpsv5rzqop5.jpg.html)

All seating deeper does is create a second problem as a poor workaround to the root cause. Loading manuals give data at a specified COA because that's within SAAMI specs for the cartridge. If you cannot stay within the dimensions of published load data, then there is another problem that should be addressed. No loading manual will suggest you seat deeper then compensate for the variation in COA as this can be VERY dangerous. Guesswork is not part of published and tested load data, and the tested data is exactly that, to maintain safety.

TC or any other style boolit (including j-words) will plunk and feed extremely well after the barrel is properly throated, you can seat out as long as your magazine will permit and they feed best in the 10mm at a longer COA. I do a lot of these and have a lot of very happy shooters here, you can send a PM for details. Your gun will run flawlessly with zero or very little leading, accuracy will improve noticeably after throating. Factory, jacketed, cast, it don't matter. It will improve across the board.

Here is a recent (yesterday) post from the last Kart barrel that was sent in:

http://castboolits.gunloads.com/showthread.php?318450-Pictures-of-barrel-throating

[slughammer]

Dan, here's the pic of it loaded to the shoulder, which again, puts the COAL to 1.216". What's your opinion?

The boolit is most likely going to scrape lead off when it enters the area it doesn't fit. If you still want to shoot them with no modifications (throating), then you could reduce the load to 40 S&W data and work up. Plan to clean it...

I would throat that barrel instead of buying another one. I doubt you'll loose any accuracy that you can detect. What kind of 50 yard groups are you getting now?

[wk5h]

What kind of 50 yard groups are you getting now?

I honestly couldn't tell you; I've never tested groups at 50yds. Mainly just around 10yds or so, and I can get 5" on a good day. The gun groups far better than I can, though, and I'm certain they would be tighter with a proper set of bags and rests.

I will say, that at ~240yds with a high hold on our range's gong and resting on the bench, I can keep the hits within a 10ft diameter of the gong with my loads. I'm more than happy with that.

I've pretty much decided, based upon what I've found and what you guys have told me, that I'm going to have the throat reamed. I found a gunsmith not too far away who does a lot of barrel work, and comes highly recommended.

[TCLouis]

IF you are seating that boolit that deep and not reducing the powder charge, I would guess your pressure is on up there.
I have never loaded for 10mm, but that seems to be an awful lot of case capacity being used up.

[wk5h]

IF you are seating that boolit that deep and not reducing the powder charge, I would guess your pressure is on up there.
I have never loaded for 10mm, but that seems to be an awful lot of case capacity being used up.

Yeah, I didn't reduce the powder, but, they were filled before I realized I was going to have to seat that deep, so, they will all go in the pull bucket.

[wk5h]

Just a follow up...

I spoke with the guy who made the bullets, and he wanted me to bring my barrel and a loaded round to him next time I was around. Yesterday, I was around, so, I stopped in. VERY nice guy, very knowledgeable, and only charged me $10 to throat the barrel. Made a HUGE difference in the round dropping in.

I gave him $20, cause I spent the next 45 minutes bending his ear on loading and gun conversation, and I still feel like I owe him more than that.