Kevin Jenkins is the excellent gunsmith who has custody of the following reamers:

1) 500 A-Square standard reamer by PPG (Pacific Precision Grinding):
35-degree shoulder
.400" parallel-sided freebore length

2) .510 JAB reamer by Dave Manson:
30-degree shoulder
.300" parallel-sided freebore length
otherwise same as 500A2
".510/460 Weatherby Improved Jenkins and Berry"

3) .510 caliber throating reamer by Dave Manson, for any throat you want: you pick the parallel-sided freebore length you want, leade is 1.5-degree.

The .510 JAB throat was designed by Dave Manson to be a best fit for the milsurp AP bullets for the 50BMG, crimped on their cannelure. Standard 500A2 dies from RCBS work fine for loading it. No custom dies needed.

If you want to seat the 750-grain Hornady A-Max out to 4.760" COL, extending the freebore a bit is a good idea. I have one that has been lengthened to 0.588" run of parallel-sided freebore.

Several members have PM-ed me about this so I called Kevin and he said it would be fine to drop his name and number here if anyone wants a 500 A2 or .510 JAB with any throat desired. He is located in Spring Hill, Tennessee, south of Nashville. His cell phone:

(615) 969-3304

Barrel twist rates?

Remember the 500A2 and 50 Peacekeeper proprietary makers recommended 1:10" twist.

The faster 50 BMG works best with 1:15" twist with the 750-grainers.

The slower .510/460 Weatherby cartridges are served best by a faster twist to deliver the same rps as the 50 BMG.

I chose 1:10" twist for my two rifles, that serve as hunting rifles primarily and target rifles secondarily.

For a primarily target oriented 500A2 or .510JAB,
I opine that a 1:12" twist would be best for delivering supersonic 750-grain A-Max bullets at 1000 yards.

RPS for 2200 fps in 1:12" twist = 2200 RPS

RPS for 2750 fps in 1:15" twist = 2200 RPS

Is my math right?

RPS for 2200 fps in a 1:10" twist = 2640 RPS

I know this 1:10" twist works well enough at 942 yards with the still supersonic 700 to 750 grainers, and it surely doesn't hinder 570-grain GSC FN bullets passing right through an 1830-pound bison from rump to throat and beyond: reliably and accurately.

RPS for the 570-grain GSC at 2450 fps in a 1:10" twist barrel = 2940 RPS

1:12" twist for a 500 A2 would be a good compromise.

Anybody want to "Do The Twist" again?
I hope not.
Rip has spoken.

Who makes that 500A2 reamer, and, what does it cost?
S

Excuse me.
The original 500 A-Square reamer that Kevin ordered on 12/02/99 was from Pacific Precision Grinding, not JGS. I have corrected the booboo. It has only chambered about three rifles.

I don't know if either of the Dave's (Kiff or Manson) was associated with PPG back then.

Dave Kiff runs Pacific Tool and Guage now.

Dave Manson left employ by a reamer making firm (??? JGS, Clymer, PPG???) and started his own business, Loon Lake Precision, which is what he was in October 2000 when he made the .510 JAB reamer for customer "Kevin Jenkins."

What I did was fire-form the .460 Weatherby cases in the rifle chambered with the 500 A2 reamer from PPG.
Then I loaded the fired brass with the 50 BMG milsurp AP bullet crimped at the cannelure.
Then gave three of these dummies to Kevin and he sent them to Dave Manson, who made the .510 JAB reamer from measuring the dummies and "voila," .510 JAB reamer.

Dave Manson changed the name of his company to "Dave Manson Precision Reamers" subsequent to Loon Lake days.

Might have something to do with the "rifle looney" phrase made famous by John Barsness.
Made "Loon Lake Precision" not cool???


I did not mean for this to be a history of USA reamer makers, but if sumbuddy who know can tell us more, have at it, please.

Yes I found the original receipt from Pacific Precision Grinding in 1999, for the 500 A-Square reamer: $147.00

You can still get a finish reamer from Dave Manson for little more.

Wildcats or "Specials"
Solid pilot: $165.00
Removable pilot: $195.00

Since Dave Manson has already made the .395 Tatanka and .395 GSC reamers, I added him to the .395 Family: www.mansonreamers.com

I must schedule time tomorrow for a call to Harry McGowen to ask him "Are we there yet?"

Trivia:

Q: Who was the gunsmith who did a few "gunsmith tips" segments on Dave Watson's original TV show, "Secrets of the Hunt" sponsored by Bushnell?

A: Kevin Jenkins.