38 Super Comp Pressure issue/question

[sbgruen]

Hello, I am just getting into Open gun shooting and picked up a STI 38Super with a .355 barrel and am reloading 38 SuperComp Brass out of it. I have been working up a load using 124gr MG JHP, Starline 38SC brass, Win SR Primers and SR4756 Powder. I started noticing a slight bulge in the brass at 7.3 gr of powder. I can see the very slight bulge in the brass and measured it at about .0005" Not much to measure but can definitely see it. The overall length is 1.250" and according to the reloading page by Jeff Maass it should be able to load to go to 8.4 to 9.2 gr to make 180 Power factor. Currently I am getting about 1282 fps or PF =159.

Question is, is it normal to see this in 38 Supers? Normally with unsupported barrels if I was to see a bulge I would say I am running too high a pressure.

Thanks in advance!!

Scott

[GrumpyOne]

What does your primer look like? That's a better indication of pressure than the case bulging, which could just be caused by a slightly oversized chamber.

Another thing, go to a lighter bullet, with an even slower burning powder. My load for 38S is 10.5 of VV N105 and a 115MG JHP, SPMP @1.235. Fantastic load. No pressure signs.

[walter hornby]

my load for a 38 super is 8.6 grains of 3N37. works well, no pressure signs.

[sbgruen]

What does your primer look like? That's a better indication of pressure than the case bulging, which could just be caused by a slightly oversized chamber.

Another thing, go to a lighter bullet, with an even slower burning powder. My load for 38S is 10.5 of VV N105 and a 115MG JHP, SPMP @1.235. Fantastic load. No pressure signs.

The primer looks fine. It is not flattened at all. I am using Rifle primers. I have a bunch of the 124 and 130 gr bullets so maybe the powder change is the better first option.

Thanks

scott

[ParaGunner]

I'm using the same bullets and powder with cci small pistol primers in a 38super case at 1.24oal. I'm using 8grns of IMR4756 to make a 171pf with no pressure signs. It sounds like some normal bulging, is the bulged cases resizing ok?

[lcs]

Hello, I am just getting into Open gun shooting and picked up a STI 38Super with a .355 barrel and am reloading 38 SuperComp Brass out of it. I have been working up a load using 124gr MG JHP, Starline 38SC brass, Win SR Primers and SR4756 Powder. I started noticing a slight bulge in the brass at 7.3 gr of powder. I can see the very slight bulge in the brass and measured it at about .0005" Not much to measure but can definitely see it. The overall length is 1.250" and according to the reloading page by Jeff Maass it should be able to load to go to 8.4 to 9.2 gr to make 180 Power factor. Currently I am getting about 1282 fps or PF =159.

Question is, is it normal to see this in 38 Supers? Normally with unsupported barrels if I was to see a bulge I would say I am running too high a pressure.

Thanks in advance!!

Scott

IMR 4756 varies lot to lot, but high pressure is not a side affect of 4756. When I first started shooting 9 Major I loaded 4756 (It does not make major) and was just about using a scraper to level the powder at the case mouth and then compressing the hell out of the load. No signs of excessive pressure. I know 38SC shooters who were filling the case on their loads also as they had barrel holes.

I think you can work your load up higher without concern. Just work up slowly. IMR 4756 is a soft shooting powder.

[sbgruen]

I'm using the same bullets and powder with cci small pistol primers in a 38super case at 1.24oal. I'm using 8grns of IMR4756 to make a 171pf with no pressure signs. It sounds like some normal bulging, is the bulged cases resizing ok?

So if I am understanding you correctly, there is some bulging that is normal, not just the overall uniform increase in the brass diameter?

Thanks

[ong45]

Don't worry about a little bulging, nature of the beast when shooting open. This is likely to get a little worse as you get closer to major, older brass also bulges more than new. I shot major( supercomp) with 4756 for years and never had any pressure problems.

[sbgruen]

Don't worry about a little bulging, nature of the beast when shooting open. This is likely to get a little worse as you get closer to major, older brass also bulges more than new. I shot major( supercomp) with 4756 for years and never had any pressure problems.

Sounds good. looks like bulging is common on some loads. I have not tried to resize any of the brass either....it may be below the die on the 550 however.

thanks again

Scott

[wide45]

Bulging is not normal. It may not be from over pressure if the chamber is oversize.

If the chamber is properly cut, there should be no bulging at all.

[al503]

Bulging is not normal. It may not be from over pressure if the chamber is oversize.

If the chamber is properly cut, there should be no bulging at all.

Unless the bbl came slightly oversize or the builder reamed the bbl slightly to aid feeding reliability.

[sbgruen]

Bulging is not normal. It may not be from over pressure if the chamber is oversize.

If the chamber is properly cut, there should be no bulging at all.

I'll measure the chamber, thanks. anyone know what the standard chamber for 38 super is of the top of their head?

thanks again,

Scott

[Foxbat]

Apparently there have been cases of people re-chambering their 9mm barrels to 38 Super or SC. Doing so will leave the chamber oversized at the bottom, by about 18 thousands.

If you try to measure the chamber, be aware that most of the common calipers will do horrible job at that. A far better way is to try several pieces of shot brass, to find one that fits tightly, and measure its outside diameter.

[G-ManBart]

I can verify the chambers on both of my .38SC guns haven't been messed with, and they both leave a slight bulge in the brass opposite the barrel hood. I've also had half a dozen people with new Open guns have me look at their brass because it looked exactly the same way....virtually identical in every case. My load is within pressure limits according to VV's guide, and surprisingly low when I ran it on Quickload. R,

[sbgruen]

I can verify the chambers on both of my .38SC guns haven't been messed with, and they both leave a slight bulge in the brass opposite the barrel hood. I've also had half a dozen people with new Open guns have me look at their brass because it looked exactly the same way....virtually identical in every case. My load is within pressure limits according to VV's guide, and surprisingly low when I ran it on Quickload. R,

I have not ID'd the location of the bulge relative to the chamber but plan to do that on Thursday Night. I suspected it might be by the extractor but I might be wrong. I'll make some brass and let you know.

Thanks

Scott

[sbgruen]

Apparently there have been cases of people re-chambering their 9mm barrels to 38 Super or SC. Doing so will leave the chamber oversized at the bottom, by about 18 thousands.

If you try to measure the chamber, be aware that most of the common calipers will do horrible job at that. A far better way is to try several pieces of shot brass, to find one that fits tightly, and measure its outside diameter.

Understood, I have access to a machinist....they have all the neat tools....some of it he even lets me play machinist on!!!

By the Bottom you are talking about the chamber closest to the rifling correct?

Thanks

[Pat Miles]

Apparently there have been cases of people re-chambering their 9mm barrels to 38 Super or SC. Doing so will leave the chamber oversized at the bottom, by about 18 thousands.

If you try to measure the chamber, be aware that most of the common calipers will do horrible job at that. A far better way is to try several pieces of shot brass, to find one that fits tightly, and measure its outside diameter.

Understood, I have access to a machinist....they have all the neat tools....some of it he even lets me play machinist on!!!

By the Bottom you are talking about the chamber closest to the rifling correct?

Thanks

Bottom is normally the six o'clock position as you are looking at the barrel from the rear.

A better way to work up high pressure loads is to use small pistol primers during the load development as they are usually a softer cup and will show pressure signs earlier than small rifle primers. After you have found the load you want then you can start using small rifle primers in the recipe.

You have a pair of outstanding eyes if you can spot a half thousandth bulge.

Pat

[Foxbat]

Understood, I have access to a machinist....they have all the neat tools....some of it he even lets me play machinist on!!!

By the Bottom you are talking about the chamber closest to the rifling correct?

Thanks

No, the bottom of the case, close to the extractor grove, because this is the area a rechambered barrel will have extra clearance.

[sbgruen]

I can verify the chambers on both of my .38SC guns haven't been messed with, and they both leave a slight bulge in the brass opposite the barrel hood. I've also had half a dozen people with new Open guns have me look at their brass because it looked exactly the same way....virtually identical in every case. My load is within pressure limits according to VV's guide, and surprisingly low when I ran it on Quickload. R,

So if I understand you correctly it is by the feed ramp?

Thanks

Scott

[sbgruen]

I can verify the chambers on both of my .38SC guns haven't been messed with, and they both leave a slight bulge in the brass opposite the barrel hood. I've also had half a dozen people with new Open guns have me look at their brass because it looked exactly the same way....virtually identical in every case. My load is within pressure limits according to VV's guide, and surprisingly low when I ran it on Quickload. R,

I have not ID'd the location of the bulge relative to the chamber but plan to do that on Thursday Night. I suspected it might be by the extractor but I might be wrong. I'll make some brass and let you know.

Thanks

Scott

Well I finally had a chance to compare 4 different loads and the locations of the bulge. They are all at the 3 o'clock position looking at the back of the chamber. I loaded and shot from a 150 PF to a 180 PF and they all were in the same locations and the same size.

This seems to be a slightly different location than others saw if I am understanding correctly their bulges are at the 6 oclock position if the chamber has been reamed to a larger size.

Where were the bulges on the guns that were not reamed?

thanks again for all the help!!

Scott

[CocoBolo]

Hey I think that Bart nailed it. Now from a just good ole country boy purspective when I started shooting 38S actually 38SC, I RO'ed some biggies and picked up everything that didn't bite, same in local matches, you lazy n leave it I snag it. So i got all this brass loaded it up and 1/3 of it won't drop check, what I call fat boys, so I borrow a CasePro and roll the bulge out. Point being that "a lot of super's" give the brass a little bulge, that is why they invented the CasePro. Reaming the chamber just makes the problem worse, giving it more room to expand.

I load mine hot to 175pf and reload them 20 or more times before they split. I don't worry about the bulge I just roll all of them.

[XRe]

WHERE is it bulged, exactly? Got a picture of the case? The brass is going to bulge out some in pretty much any workable chamber. The question is, can you get it back out with a sizing die or not...

[blaster113]

my newish Open gun has a Schuemann Classic .355 barrel; most of my .38 SC brass has a small bulge near the bottom of the case near the rim. I only use the regular Dillon .38 Super size die to resize and havent had any problems as it takes out that tiny bulge. Using SR primers in my 170pf loads and havent seen any signs of excessive pressure like flattened/cratered primers, etc. If my chamber is a tiny bit loose either from the manufacturer or builder, I'll take that tradeoff for 100% reliability which I have had thus far.

[sbgruen]

WHERE is it bulged, exactly? Got a picture of the case? The brass is going to bulge out some in pretty much any workable chamber. The question is, can you get it back out with a sizing die or not...

I'll try and get a picture that shows it. Have not check to see if it resizes out, just started loading for it and working up a load.

Thanks

Scott

[XRe]

WHERE is it bulged, exactly? Got a picture of the case? The brass is going to bulge out some in pretty much any workable chamber. The question is, can you get it back out with a sizing die or not...

I'll try and get a picture that shows it. Have not check to see if it resizes out, just started loading for it and working up a load.

Thanks

Scott

The thing is, the load you're describing should be well within what would be SAAMI pressure spec for that cartridge (if .38 Supercomp had a SAAMI spec). You almost certainly don't have a pressure problem. I suspect you're describing normal case expansion due to firing. My only concern would be that your chamber is potentially too large, or too relieved at the ramp. The former causes your brass to wear out prematurely and will affect accuracy. The latter can cause a bulge that can be more difficult to remove with a sizing die. You probably don't have either problem, and are just misinterpreting what you're seeing, though.

Contrary to what's stated above, with a chamber that's even remotely close to spec, a CasePro is a waste of money for Supercomp. I've seen nasty bulges in cases that were shot in a 9x23 chamber, but those were the only ones that a regular ol' Dillon die wouldn't resize right back to normal.