45ACP Gas Blow Back

[Foto Joe]

I load almost exclusively cast lead boolits but yesterday I came across a box of Hornady XTP-JHP's 185gr. I grabbed 'em up and decided to use them to load self defense rounds for my carry guns.

I couldn't come up with the data for the exact bullet so I used Hodgdons data for JSWC's over AutoComp. Since I didn't have the exact data I started low at 7.0gr for a dozen and 7.3gr for a dozen. I took them out and chronographed them this afternoon. The 7.0's averaged 822fps with a standard deviation of 17fps and the 7.3's averaged 897fps with a standard deviation of 13. They were loaded with unfired Starline brass and RWS primers with a COL of 1.218". The rounds were fired from a S&W Government 1911.

I was pleasantly surprised with the low standard deviation, especially on the 7.3gr loads. The groups were less impressive with the 7.3gr being 2" at 15 yards but given that they are SD loads I can live with that.

What's got me scratching my noggin though is the gas blow back that I appear to be getting with loads that are pretty near max for that bullet weight according to Hodgdon. I'm quite sure that I could probably eliminate the blow back by increasing the charge but since I'm a whole .1gr off of max for the bullet weight I'm a little hesitant to play crash test dummy.

The picture could be better but hopefully you'll be able to see what I'm talking about.​

 

[sexybeast]

I've never used autocomp and have no idea how fast it is.
Try something faster, go for midrange and see if it happens again. 185's are light and have always been kind of snappy in my 45. Try 5-5.2gr of titegroup or bullseye with 185's.

 

[Walkalong]

While some .45 ACP loads will show less of that, it isn't all that uncommon.

 

[blarby]

You probably aren't getting enough seal, and thus, sooty cartridges. I get his when I'm too low on charge in most of my 45ACP offerings. Once I dial up, it usually goes away. You might also be getting a weird burn, or just too much gas.

I would try another powder.

FWIW, autocomp is not listed on Hornadys powder table for that bullet.


I dont use autocomp in 45 either. I've pretty much settled on w231/hp38, and Unique. Titegroup and Bullseye are popular powders here for that cartridge as well.

 

[gamestalker]

Although that isn't all that unusual, it can be reduced by switching to another powder. Is the soot obviously heavier on one side of the case? If so, AC might be a position sensitive powder for that cartridge, or it could also be that it isn't producing a long enough pressure curve, thus creating a poor seal. I don't think I've ever used it either, so can't say with any experience beyond that.

GS

 

[ljnowell]

Try Power Pistol.

 

[Steve C]

Your load is right at what Hodgdon lists.

Carbon scouring on the case happens with light charges and marginal slow powders that do not achieve sufficient pressure to seal the case tight enough in the chamber to prevent the gasses from flow back around the case. You may want to try a WLP primer and see if that doesn't give you some more pressure and velocity. Otherwise I'd get a different powder.

Personally in a defense round I want 1,000 fps + from a 185gr JHP which 7.7grs of Unique produces nicely.

 

[ArchAngelCD]

As the others have said, you might need to use a different powder but if you're happy with the results otherwise I wouldn't let slightly dirty cases bother me.

 

[Foto Joe]

Since these are self defense rounds I'm not too worried about sooty cases, I'm just a little curious as to why being so close to the max load for the bullet weight I would fail to get a good seal. Interestingly enough, the gun itself after firing a couple of dozen rounds is immaculately clean. I under charged some lead boolits last week working on plinkers and sooted up the gun so bad that it took an hour to clean it. These loads aren't leaving ANY unburned powder or sooting in the gun itself, just on the brass.

Unfortunately my selection of powders is pretty restricted. I've got a decent supply of AutoComp, some 700X which seems to have disappeared from the shelves and a reasonable supply of TrailBoss which makes for a really dirty 1911.

As Steve C mentioned, I would like to get closer to 1k fps if possible. I think what I'll try next is to max out at 7.4gr and switch over to Win or CCI primers and see what kind of difference if any I get.

 

[ArchAngelCD]

Joe,
AutoComp was designed to be very clean burning because it was meant for use with compensated handguns. I'm not surprised at how "immaculately clean" the gun is after shooting ammo made with AutoComp.