Proper throating

C

chino69

Guest
Fellows,
I'm having two 1 in 8 Kreiger barrels chambered in .22-250 AI to shoot 80 grn. bullets. My gunsmith told me to give him a couple of cases with the bullet I intend to shoot seated where I want it and he will use a throating reamer to set it up for my bullet. Here's my question. I want to try 80 grn. Hornady A-Maxes, 80 grn. Sierra Match Kings, and 80 grn. Berger VLDs. Should I seat one bullet each in three different cases to the depth I want and let him take the average for the throat?
Thanx in advance,
Chino69
 
I would agree with throating for the shortest bullet and adjust your loading for others... I also would not seat the bullets way out and throat it... the more rifling removed in throating, the shorter your barrel life accuracy will be. Try and set a happy medium bullet depth so as the rifling wears away you can chase it by seating the bullet out farther until the neck won't hold it anymore...
 
Throating

Dennis Sorensen said:
I would agree with throating for the shortest bullet and adjust your loading for others... I also would not seat the bullets way out and throat it... the more rifling removed in throating, the shorter your barrel life accuracy will be. Try and set a happy medium bullet depth so as the rifling wears away you can chase it by seating the bullet out farther until the neck won't hold it anymore...
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Dennis,
Thank you for your reply. Here's where I have another question. If I have the throating established for the shortest bullet i want to shoot, won't this put longer bullet bases beyond the neck/shoulder junction? I'm just trying to establish a happy medium and have the best of both worlds, if that's possible.

I understand the piece about establishing enough to chase the rifling as the throat erodes. Any additional info. would be greatly appreciated.
Chino69
 
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You can't have a perfect throat length for short and long bullets... it is a bit of a compromise ... if I am going to use long and short bullets, I prefer to have the long ones stuffed into the case a bit more so the shorter ones still have lots of case neck holding them... you have to make the decision on where the happy medium is ... it just makes the gunsmiths job easier if you give a couple of fully sized dummy rounds with the same bullet seated where you want it ...
 
Chino

Take a pair of calipers and lock them at .223" may be .222". Insert a bullet and scribe a line around the ogive on all the bullets you want use. That will give you a good estimate of the bearing surface length. Lay them beside a case neck and compare the various lengths. I think you'll be able to a decision then as to which bullet to throat to.

Dave
 
Don't worry. With a 22-250 AI if the long bullets are a little deep in the case to begin with, it won't be too long before the throat advances and you can seat them out farther.
 
throating

Dave Tooley said:
Chino

Take a pair of calipers and lock them at .223" may be .222". Insert a bullet and scribe a line around the ogive on all the bullets you want use. That will give you a good estimate of the bearing surface length. Lay them beside a case neck and compare the various lengths. I think you'll be able to a decision then as to which bullet to throat to.

Dave
Click to expand...

Dave,
I have a Sinclair bullet comparator that is hexagonal for measuring the ogive of various calibers. I use it for bullet seating lengths and recording these values so that I can always seat to the ogive of the bullet and the bottom of the case. The holes were reamed with throating reamers. Let me see if I have this right: pick the bullets I want to use, insert them into the hole, and then scribe a line circumferentially around the bullet at the interface of the bullet ogive and the comparator hole. Is the bearing surface length the bullet area away from the bullet tip and below the scribed line (the part that goes into the neck)? What am I looking for beyond that?
Chino69
 
Chino

I don't know the diameter of the holes in the Sinclair tool. The closer to bullet diameter the hole is, the closer you'll be to the bearing surface length. The bearing surface is the body of the bullet, the cylinder section between the ogive and the boat tail. All this exersise will do is tell which is the shortest body bullet and which is the longest. All three may be close to the same length and one throating will work for you.

Dave
 
throating

Dave Tooley said:
Chino

I don't know the diameter of the holes in the Sinclair tool. The closer to bullet diameter the hole is, the closer you'll be to the bearing surface length. The bearing surface is the body of the bullet, the cylinder section between the ogive and the boat tail. All this exersise will do is tell which is the shortest body bullet and which is the longest. All three may be close to the same length and one throating will work for you.

Dave
Click to expand...

Dave,
Thank you for you reply; I get it! I'll do what you suggest and load that bullet accordingly. They are all going to be 80 grn. bullets (Hornady A-Max, Sierra Match Kings, and Berger VLDs) so they might be pretty close. So I pick the shortest of these, the cylinder section between the ogive and the boat tail, seat it into a case to the depth I want and give it to my gunsmith. Sound Right?
Chino69
 
throat erosion

gzig5 said:
Don't worry. With a 22-250 AI if the long bullets are a little deep in the case to begin with, it won't be too long before the throat advances and you can seat them out farther.
Click to expand...

I hear that! I began breaking in a new 1 in 12" Pac Nor Super Match barrel in .22-250 AI. Monitoring the throat and rifling during the break in process with a borescope revealed firecracks after just 40 rds. By contrast, a 1 in 12" Pac Nor Super Match in .308 showed no evidence of firecracking after 80 rds. Yeah, the Ackleys are fast but at a price.
Chino69
 
What I have done

Select all the different bullets you may want to shoot in this rifle.

Seat each bullet with the measurement to ogive of the bullet at the same distance from the base of the case. The OAL will be different with each bullet.

Longer bullets will seat deeper in the case and shorter will not seat as deep.

A very simple task.

We did this with a 6.5 with different weight bullets from 95 to 140 grains. The design of the reamer turned out sweet.
 
Throating

I would like to thank all who contributed information to enable me to make up dummy rounds for throating. Here's what I did for the benefit of those who can learn something, as I did:

1) I have two Kreiger 1 in 8 inch twist barrels that are going to be chambered in .22-250 AI to shoot 69 grn. to 80 grn. bullets. One barrel will be throated a little different than the other.

2) Using a Davidson bullet comparator from Sinclair, I inserted the bullet and scribed a line where the ogive of the bullet interfaced with the hole in the comparator. This tool is the one that looks like a big nut and has holes for six different calibers that are reamed with throating reamers.

3) I placed the bullets with the base against a machined surface so that I could compare the bearing surface of the various bullets. The bearing surface is from behind the scribed line to the base of the bullet. I picked the shortest bearing surface bullet, seated it in a dummy round and gave it to my gunsmith.

4) One of the barrels will be throated to shoot 80 grn. bullets and I chose 80 grn. Sierra Match Kings, 80 grn. Hornady A Maxes, and 80 grn. Berger VLDs. The Sierra M.K. had the shortest bearing surface so this was my choice for the dummy round. The Hornady & Berger were close enough to call the same. I performed the same step for the other barrel with 69 grn. up to 75 grn. bullets.

Chino69
 
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