Blowby gas

Darth AkSarBen · November 17, 2008, 12:21 AM

On my handloads for my .45 ACP that I shoot out of my Taurus 24/7 Pro, I have a question. I am loading with 4.7 gr of Titegroup, CCI LP Pistol primers, and various brass, topped with a 185 gr Ranier, copper clad bullet. Shoots a pretty good group, but on every single case there is evidence of gas blowby that I don't see with commercial ammo. Am I not getting enough powder for case expansion to seal the chamber when I shoot? Do I need to up the charge weight to expand out the brass to seal? primers look very good, not pressure signs at all.

**Unclenick** · November 17, 2008, 01:42 AM

Maybe. Are you just seeing stains on the cases, or is there actual crud there? In the latter case, incomplete combustion is suggested. Very odd for a fast powder. If the cases have been reloaded many times, you may be seeing some work hardening make them more difficult to expand? You could try slowly working up toward 5.5 grains of Titegroup, but if you are wanting to have a light target load, that would seem to defeat your purposes. You could switch to a faster powder. About 3.8 grains of Hodgdon Clays will raise the pressure to normal hardball pressure, though you will lose a little velocity. It will have less recoil from that.

Darth AkSarBen · November 17, 2008, 06:44 AM

What I am seeing is staining on the cases. This is the first time reloaded after factory for these rounds. The crimp is from a Lee 3 die carbide die set. Perhaps the crimp is too light? I belived my measurement was .471

Magtech factory ammo in 230 gr does not do the blow by gas. Seemed like I read somewhere that if you crimp the .45 a bit tighter the pressures build fast enough to create seal quicker. Lack of seal would seem to be counter productive to target loads as "some" gas escaping reduces the overall pressure from shot to shot, but mabe not exactly the same.

Sevens · November 17, 2008, 08:15 AM

I've had success with both 5.1 and 5.4 grain loads of Titegroup pushing a 200 gr LSWC in .45, so it would be my opinion that your load is a pipsqueak and you could/should work that load up a bit and check the results.

F. Guffey · November 17, 2008, 11:29 AM

Darth AkSarBen, not for everyone and will not drag others into this but, I crimp the 45ACP with a sizer die for one pistol, it likes new ammo, when I suspect a case is not sealing the chamber, I cover the receiver with a white cloth and check after firing, this helps determine a problem, sometimes it is the diameter of the barrel, worn etc.,

I do not full length crimp, just enough to remove the evidence a bullet has been seated, just like the factory ammo, and, the dimensions when compared are the same.

Richard Lee is a big fan of crimping, he wants the powder to get started before the bullet moves.

F. Guffey

WESHOOT2 · November 17, 2008, 12:24 PM

It is from your powder choice (which is why you don't see it from 'factory' ammo).

Suggest ever-so-slightly increasing crimp (no less than .468"), slightly increasing charge weight (no more than 5.4g), or using a better powder choice.

TEDDY · November 18, 2008, 09:07 PM

you dont crimp with fmj.but you do with lead.I load target loads 3.6 gr 700X
and 200 gr SWC.45acp was made for bullseye why all the other powders are used I cant figure.I use 700X as it is same? as bullseye.also I first used it because I got it for $1.00 can,now I have 20 lbs.a 45 acp can handle a heavy load,but aanother cart would use anothe powder.

Darth AkSarBen · November 18, 2008, 10:31 PM

I've read elsewhere on the forums, that crimping gives the powder time to really get going, as it builds pressure faster, and does a better job at expanding the brass to prevent blow by gas.
I just did not want to cause too much indentation on these Ranier bullets.

D. Manley · November 18, 2008, 11:57 PM

Quote:

On my handloads for my .45 ACP that I shoot out of my Taurus 24/7 Pro, I have a question. I am loading with 4.7 gr of Titegroup, CCI LP Pistol primers, and various brass, topped with a 185 gr Ranier, copper clad bullet. Shoots a pretty good group, but on every single case there is evidence of gas blowby that I don't see with commercial ammo. Am I not getting enough powder for case expansion to seal the chamber when I shoot? Do I need to up the charge weight to expand out the brass to seal? primers look very good, not pressure signs at all.

IMHO, increasing the crimp will likely have no effect on the "blowby" problem you describe and doing so could well result in "resizing" your (very soft) Rainier plated bullets and destroying accuracy. I use .472 on Rainiers and find .471/.470 or so leaves a visible (but harmless) crimp ring and below .470 often leaves a measurable difference on the bullet.

Bottom line, you aren't getting enough pressure to seal the chamber walls, common in the fast powder/low pressure cartridge combination. TG compounds the phenomenon because its not only pretty fast, it also has a high (and maybe, highest) nitroglycerin content and is very hot-burning. Your load is .3 grain below Hodgdon's recommended starting load of 5.0 grains which, translates to a significant amount at the low charge weights of Titegroup. Bump the load up gradually and you can probably reduce it but don't be surprised if you don't eliminate it entirely. I don't use it much in .45 but when I do, its with 230's and I still get "some" blowby even at higher pressures. The effects are in all likelyhood, purely cosmetic...this is a common occurence (especially with TG) but I've never heard of anyone having any throat erosion as a result and there's an awful lot of people using it even with, reduced loads.

BigJimP · November 19, 2008, 06:52 PM

Rainiers own website - reminds you to use data for lead bullets - not jacketed bullets because they use an electroplating process and their bullets are a lot softer than typical jacketed bullets.

The crimp issues aside / I wouldn't recommend getting up around 5.5 grains of TiteGroup at all.

I like TiteGroup - but I wouldn't load a rainier bullet past the minimum recommendation for a jacketed bullet in Hodgdon's load tables.

November 17, 2008, 12:21 AM	#1
Darth AkSarBen Member Join Date: September 9, 2008 Location: Near Fennville, MI USA Posts: 82	Blowby gas On my handloads for my .45 ACP that I shoot out of my Taurus 24/7 Pro, I have a question. I am loading with 4.7 gr of Titegroup, CCI LP Pistol primers, and various brass, topped with a 185 gr Ranier, copper clad bullet. Shoots a pretty good group, but on every single case there is evidence of gas blowby that I don't see with commercial ammo. Am I not getting enough powder for case expansion to seal the chamber when I shoot? Do I need to up the charge weight to expand out the brass to seal? primers look very good, not pressure signs at all. __________________ Vern Sic Semper Tyrannis http://Taurus45ACP.com Sig Sauer 522 "Classic" AR Performance 16" 5R 1:11.25 twist barrel in 6.8 SPC, 80% lower, along with LOTS of other things.

November 17, 2008, 01:42 AM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Maybe. Are you just seeing stains on the cases, or is there actual crud there? In the latter case, incomplete combustion is suggested. Very odd for a fast powder. If the cases have been reloaded many times, you may be seeing some work hardening make them more difficult to expand? You could try slowly working up toward 5.5 grains of Titegroup, but if you are wanting to have a light target load, that would seem to defeat your purposes. You could switch to a faster powder. About 3.8 grains of Hodgdon Clays will raise the pressure to normal hardball pressure, though you will lose a little velocity. It will have less recoil from that. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

November 17, 2008, 06:44 AM	#3
Darth AkSarBen Member Join Date: September 9, 2008 Location: Near Fennville, MI USA Posts: 82	What I am seeing is staining on the cases. This is the first time reloaded after factory for these rounds. The crimp is from a Lee 3 die carbide die set. Perhaps the crimp is too light? I belived my measurement was .471 Magtech factory ammo in 230 gr does not do the blow by gas. Seemed like I read somewhere that if you crimp the .45 a bit tighter the pressures build fast enough to create seal quicker. Lack of seal would seem to be counter productive to target loads as "some" gas escaping reduces the overall pressure from shot to shot, but mabe not exactly the same. __________________ Vern Sic Semper Tyrannis http://Taurus45ACP.com Sig Sauer 522 "Classic" AR Performance 16" 5R 1:11.25 twist barrel in 6.8 SPC, 80% lower, along with LOTS of other things.

November 17, 2008, 08:15 AM	#4
Sevens Senior Member Join Date: July 28, 2007 Location: Ohio Posts: 11,756	I've had success with both 5.1 and 5.4 grain loads of Titegroup pushing a 200 gr LSWC in .45, so it would be my opinion that your load is a pipsqueak and you could/should work that load up a bit and check the results. __________________ *Attention Brass rats and other reloaders:* I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.

November 17, 2008, 12:24 PM	#6
WESHOOT2 Senior Member Join Date: February 20, 1999 Location: home on the range; Vermont (Caspian country) Posts: 14,324	titesoot It is from your powder choice (which is why you don't see it from 'factory' ammo). Suggest ever-so-slightly increasing crimp (no less than .468"), slightly increasing charge weight (no more than 5.4g), or using a better powder choice. __________________ . "all my ammo is mostly retired factory ammo"

November 17, 2008, 11:29 AM	#5
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	Darth AkSarBen, not for everyone and will not drag others into this but, I crimp the 45ACP with a sizer die for one pistol, it likes new ammo, when I suspect a case is not sealing the chamber, I cover the receiver with a white cloth and check after firing, this helps determine a problem, sometimes it is the diameter of the barrel, worn etc., I do not full length crimp, just enough to remove the evidence a bullet has been seated, just like the factory ammo, and, the dimensions when compared are the same. Richard Lee is a big fan of crimping, he wants the powder to get started before the bullet moves. F. Guffey

November 18, 2008, 09:07 PM	#7
TEDDY Junior member Join Date: December 10, 2006 Location: MANNING SC Posts: 837	crimping you dont crimp with fmj.but you do with lead.I load target loads 3.6 gr 700X and 200 gr SWC.45acp was made for bullseye why all the other powders are used I cant figure.I use 700X as it is same? as bullseye.also I first used it because I got it for $1.00 can,now I have 20 lbs.a 45 acp can handle a heavy load,but aanother cart would use anothe powder.

November 18, 2008, 10:31 PM	#8
Darth AkSarBen Member Join Date: September 9, 2008 Location: Near Fennville, MI USA Posts: 82	I've read elsewhere on the forums, that crimping gives the powder time to really get going, as it builds pressure faster, and does a better job at expanding the brass to prevent blow by gas. I just did not want to cause too much indentation on these Ranier bullets. __________________ Vern Sic Semper Tyrannis http://Taurus45ACP.com Sig Sauer 522 "Classic" AR Performance 16" 5R 1:11.25 twist barrel in 6.8 SPC, 80% lower, along with LOTS of other things.

November 19, 2008, 06:52 PM	#10
BigJimP Senior Member Join Date: February 23, 2005 Posts: 13,195	Rainiers own website - reminds you to use data for lead bullets - not jacketed bullets because they use an electroplating process and their bullets are a lot softer than typical jacketed bullets. The crimp issues aside / I wouldn't recommend getting up around 5.5 grains of TiteGroup at all. I like TiteGroup - but I wouldn't load a rainier bullet past the minimum recommendation for a jacketed bullet in Hodgdon's load tables.