Corbon DPX accuracy

[DBR]

I recently sighted in a couple of 16" 1:7 AR15s at 100 yds. One had an Aimpoint ML2 the other had a good quality 1.5-5x scope. After sighting in with Hornady TAP 75gr "Personal Defense" ammo which got better than 1.5 MOA with both guns for 3 shot groups from a cold barrel, I shot Corbon 55gr DPX 3 shot groups from both guns to see if POA was different (cold barrel).

I was not impressed by the results. Both guns shot "patterns" with the Barnes bullet averaging about 8".

Here is what I want to know: I have heard that Barnes bullets want a clean barrel. Does this mean that if I use a more common round as my "standard" like the Hornady 75gr TAP I cannot count on reliable accuracy if I shoot some Hornady and then switch to the Barnes bullet for more barrier penetration without the opportunity to clean the barrel?

This "problem" occurred with two different rifles on the same day at the same time with the same ammo from the same 20rd mag.

Both barrels started off clean. Part of my original test was to determine if a "clean" barrel need "fouling" shots to settle down after cleaning. At least for these barrels they did not.

[alistaire]

Perhaps these barrels don't like light bullets. Try the 62 grain DPX. Have you tried any other 55gr bullets with these to weapons?

[DBR]

Yes, I have shot 55gr Black Hills and Lake City. The Black Hills averages 1-2" and the XM193 goes about 3". These are 5 shot groups from a bipod and bench.

After I posted I spoke with the folks at Corbon. They said that Barnes recommends a clean barrel and cleaning about every 20rds for best results. They were surprised though by the wide "pattern".

I will repeat this test the next time I shoot at 100yds.

[BushmasterFanBoy]

I shot the Federal Premium Loading of the TSX round through my 1/9" 14.5" BM carbine, it grouped to a similar size as Privi at 50yards, (1-1.5" using my M4s)

I was impressed that it shot to virtually the same point of impact as the 55gr. FMJ (this is the reason I decided on a 55gr. load) but didn't get a chance to group it at 100 yards for accuracy. I may buy another box for accuracy testing, but just 120 rounds cost me $200!

ETA: This gun is run pretty dirty, and the barrel's last good cleaning was ages ago. I was worried that groups might suffer, but at 50 yards, the ammo seemed to slightly shoot tighter than the Privi I normally use.

[SMJayman]

I've had good results with the 62gr TSX bullet as handloaded by me, but I have not tried the Corbon loadings. Try out the 62s and see if they do any better, although if the TAP runs for you, I don't see any pressing need to monkey with the Corbon loads....

[DBR]

I wanted to use the DPX loads for 200-250yd coyote shots. Hopefully they would be effective beyond "fragmentation" range. Two other choices are 60gr Nosler partition either handloaded or from Federal and one of the new Speer Gold Dot loads.

Both of the rifles I used are on the better side of service grade AR accuracy with most ammo averaging about .75-2 MOA at 100yds for 5 shot groups.

On the same day I shot the Corbon through the ARs I sighted in my 243 Winchester Model 70 Classic Feather Weight. Shooting Federal 85gr Barnes TSX from a cold barrel each 3rd group (five in all) was less than 1" at 100yds. This surprised me!

[Molon]

The problem could be something as simple as your barrel just doesn’t like the TSX bullet. I’ve tested the 62 grain and 70 grain TSX bullets and the bullets themselves are capable of some fine accuracy. I don’t see why the 55 grain TSX should be much different.

Hand-loaded 62 grain TSX rounds produced a sub-MOA 10-shot group at 100 yards from an already fouled barrel.



The COR-BON factory loaded 62 grain DPX load produced a 10-shot group with an extreme spread of 1.75” from an already fouled barrel.



Hand-loaded 70 grain TSX rounds turned in a 10-shot group with an extreme spread of 1.12” from 100 yards.

[BAC]

Which rifle did you use for those, Molon? (curious about twist rate is all, or if you've noticed a difference between twist rates and precision...)


-B

[Ned Christiansen]

Mang!

That first group is more like .74 if you take out that wild one. 9 into .74..... that kind of accuracy eludes me but for an occasional fluke group.

Molon, what is your procedure for bench shooting, I mean, bags or bipod, let it slide in recoil or buck it up, single-loading rounds or careful semi-auto fire?

[DBR]

Molon:

Thanks for chiming in. I too have had excellent accuracy from the Barnes bullets in 243, 30-06 and 30 Carbine after firing other ammo. Maybe the stars just weren't right or maybe there is something not right with this box of ammo - all were from the same box.

I will do a repeat from a clean barrel and a barrel that has fired the same Hornady TAP and see what happens.

I posted because I wanted to see if anyone else had experienced this unusual result.

Thanks