.308 Winchester Firelapping Ammo
Arizona Ammunition Company

16 February 1999
By peteR

I decided early last year to attempt to improve accuracy with my Remington 700 Police DM by firelapping the barrel. After a bit of research it was determined this would be done with some preloaded ammunition obtained from Mr. Jim Schmidt at The Arizona Ammunition Company. (Mr. Schmidt was in the process of loading some .50 BMG ammo to be used in a popular drugstore gun magazine test when I called, and still managed to break free and politely answer my inane questions, and give me both a production and delivery date to my front door) I did not feel that I had the time, patience, or skill to manufacture the ammunition myself. Subtle things like not having to worry about the projectiles' abrasive coating getting into my very expensive Redding Competition reloading dies comes to mind, and its easy to figure such endeavors are best left to someone with extensive experience fabricating such a specialized round.

Mr. Schmidt re-iterated a number of topics that regularly come forth during the sale of firelapping ammo that are worth mentioning here in cyber-space:

  1. If you roll your own, don't exceed 2000 fps for muzzle velocities
  2. Follow The Directions Implicitly, do not deviate from them!
  3. Do not fire more than one Firelapping series (50 rounds) through your rifle, more will not improve accuracy.
  4. Don't waste time with a high grade custom barrel, they are already done and the risk of damaging a professional lapping/polishing job is quite possible.

The arrival of the shipping box revealed a fifty round plastic ammo box nestled in foam plugs, that consisted of assorted once fired Federal, R-P, and Winchester brass loaded with abrasive impregnated projectiles neatly color coded and packed with a foam lid liner. A light proprietary charge of unidentified smokeless powder and the primers were standard Federals according to an internal source. The brass was carefully visually inspected and no abnormalities were apparent and the primers were set to a uniform depth in the cases. Powder charge weight, run out, and overall length were not checked as I did not wish to risk contaminating any of my measuring or indicating equipment with the abrasives./

The following color coding is used to make this task simpler:

10 BLACK tipped
Coarse
220 GRIT
10 RED tipped
Medium
400 GRIT
10 WHITE tipped
Fine
800 GRIT
20 BLUE tipped
Polish
1200 GRIT





One thing that hasn't been mentioned by any popular firearms writer is the caveat that all preloaded or existing cartridge brass used for fire lapping should be discarded after use. Kind of common sense really, as brass will impregnate with the utilized abrasives during the loading and firing process. Each of the fifty Arizona Ammunition cases has a cannelure applied to the outside of the case above the web for ready identification which is a nice touch and allows quick culling for destruction. (I put my kids to work on them with a ball peen hammer as soon as I got home from the range.)

The recommended procedure is to carefully clean both the barrel and action of all residue between each shot string with high quality bore cleaners of both the liquid and mild abrasive type (Rem-Clean, JB bore paste, Iosso paste et. al.) I followed these steps for the fire lapping procedure and cleaning and added one more simple one. The barrel was flushed with copious amounts of rubbing alcohol (one complete 16 oz. bottle) between each grit of lapping compound. A funnel equipped with a 24" piece of 3/8" automotive fuel tubing was inserted through the rear of the receiver to deluge flood the barrel and chamber. This was then followed by alcohol saturated patches, dry patched, and after completely air drying, a FP-10 saturated patch was run through the barrel followed by three more dry patches.

All of the firelapping shots were carefully chronographed and aimed at a specific target just to see if anything out of the ordinary would result. Its a very good thing that I did. The first shot went "Pop", recoiled like a .22 Hornet , and the Oehler 33P coughed out a velocity of 1268 fps. The shot impacted 7 3/4" below the point of aim, hit the metal target frame, and spattered three additional test targets with secondary projectiles and spalling!

The Oehler got a fresh battery (just in case), and the next nine shots raised the ante to 1350 fps. I adjusted to a higher aiming point on the target for the next 49 rounds noting that they fell within a roughly 4" diameter shot cluster for the fifty rounds fired.

The total velocity range for the fifty rounds was recorded at 15' from the muzzle:
Color
Hi
Low
ES
Avg.
SD
Black
1433
1241
192
1350
85
Red
1454
1310
144
1406
41
White
1451
1276
175
1412
50
Blue
1522
1257
265
1438
52

After completion of the firelapping process with all fifty rounds, the bore and action was once again cleaned very thoroughly with Shooters Choice, Quick Scrub III, and JB bore cleaner and a final dousing with a bottle of rubbing alcohol.

Over a lengthy period of time, ten cold barrel shots integrated with each of ten 5 shot groups were fired at 100 yards and the results tabulated and compiled in a 3 ring binder. The CBS were noted, and then the remaining four rounds fired to make up each of the groups with a light Shooters Choice cleaning between each group. No "Foulers Game" here folks, all the shots were honestly accounted for on paper and as part of each group.

Curiously the shot clusters opened up significantly in a radial pattern over the first fifty rounds fired after lapping, but the claims of more consistent (and critical) first round shots, and quicker bore cleaning have seemed to hold up. I believe that this may be partially due to the squeaky clean bore getting settled in again and "seasoning" a little bit. The rifle will now keep each CBS within a 1" paster at 100 yards and close enough to a center punch that any error is probably me. Before the process, there was a notable consistent 1/4" to 3/4" or so vertical deviation for the CBS with any of the four factory ammos (168 -175 gr.) used to establish preliminary field accuracy.

Is it worth the money ($100+ dollars per box ) to buy firelapping ammunition and attempt smoothing a factory barrel? I believe the jury is still out on this one, at least until another 1000 rounds have made it through the barrel and all Cold Barrel Shots and groups have been carefully measured /averaged but it seems to be a viable alternative to rebarreling for those on a budget.




Arizona Ammunition Company
21421 North 14th Avenue Suite E
Phoenix, AZ. 85027
(602) 516-9004


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