Why is my pump over-pressuring?

Reloading equipment, methods, load data, powder and projectile information.

Why is my pump over-pressuring?

Post by Medic » 26 Feb 2018, 5:29 pm

Hey guys,
So I had a bolt 223 that I could shoot up to 15.5 grains of AP100 in for a velocity of 3100 with a 55grain pill.
I backed it off to 14.5 for an overall 2950 average safely and consistantly in my howa 1500.
I worked up similarly in my remington pump 7615 today and noticed massive ejector marks, stuck cases, blown primers. I've tried different COAL that had a marginal effect but honestly, what could be causing this?

I have another load of 18.5 grains 2205 which not only hits 3000fps but also cycles and AR. I thought I might go back to it because its a bit lower pressure, but i have 2kg of AP100.

The 308 runs just fine with 32 grains of 2205 @ 2450 (125grain tnt) or 22/23 grains AP100 @ 2250. Great loads for plinking and hunting particularly if you shoot alot which is almost always with a pump. Those loads were the same and ran fine in a 308 bolt.

So yeah, what the hell is with the 223. It over pressured so much it stuck the ejector back, I gotta pull it apart and fix it. What the hell? How can the chamber be so damn different???
Ideas?
P.s: I do these downloads because its MUCH cheaper to shoot and I shoot ALOT. They still smack things at 2750FPS so yeah, I wanna stick with them. Ideas?
Medic
Private
Private
 
Posts: 74
Queensland

Re: Why is my pump over-pressuring?

Post by bladeracer » 26 Feb 2018, 6:02 pm

Medic wrote:Hey guys,
So I had a bolt 223 that I could shoot up to 15.5 grains of AP100 in for a velocity of 3100 with a 55grain pill.
I backed it off to 14.5 for an overall 2950 average safely and consistantly in my howa 1500.
I worked up similarly in my remington pump 7615 today and noticed massive ejector marks, stuck cases, blown primers. I've tried different COAL that had a marginal effect but honestly, what could be causing this?

I have another load of 18.5 grains 2205 which not only hits 3000fps but also cycles and AR. I thought I might go back to it because its a bit lower pressure, but i have 2kg of AP100.

The 308 runs just fine with 32 grains of 2205 @ 2450 (125grain tnt) or 22/23 grains AP100 @ 2250. Great loads for plinking and hunting particularly if you shoot alot which is almost always with a pump. Those loads were the same and ran fine in a 308 bolt.

So yeah, what the hell is with the 223. It over pressured so much it stuck the ejector back, I gotta pull it apart and fix it. What the hell? How can the chamber be so damn different???
Ideas?
P.s: I do these downloads because its MUCH cheaper to shoot and I shoot ALOT. They still smack things at 2750FPS so yeah, I wanna stick with them. Ideas?


Shorter throat maybe? Could be pushing the bullet back into the case or jamming into the lands and raising pressure.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 12655
Victoria

Re: Why is my pump over-pressuring?

Post by Oldbloke » 26 Feb 2018, 7:14 pm

What Ben said.
The greatest invention in the history of man is beer.
https://youtu.be/2v3QrUvYj-Y
Member. SFFP, Shooters Union.
SSAA, the powerful gun lobby. :lol: :lol: :lol: :lol:
Hunt safe.
User avatar
Oldbloke
Field Marshal
Field Marshal
 
Posts: 11192
Victoria

Re: Why is my pump over-pressuring?

Post by sungazer » 27 Feb 2018, 7:41 am

It could have a little but to do with the powder you are using to. A really fast powder is going to burn when the bullet is possibly still in the case while the correct powder is still burning even once the bullet has left the case and pressure has reduced. Why it happens in your pump rather than the bolt the reasons given already sound more like it. Still I would try the proper powder and see what happens.
sungazer
Sergeant Major
Sergeant Major
 
Posts: 1525
Other

Re: Why is my pump over-pressuring?

Post by Oldbloke » 27 Feb 2018, 11:16 am

Remington pump 7615 might be rear locking?
If so that would explain it.
The greatest invention in the history of man is beer.
https://youtu.be/2v3QrUvYj-Y
Member. SFFP, Shooters Union.
SSAA, the powerful gun lobby. :lol: :lol: :lol: :lol:
Hunt safe.
User avatar
Oldbloke
Field Marshal
Field Marshal
 
Posts: 11192
Victoria

Re: Why is my pump over-pressuring?

Post by sungazer » 27 Feb 2018, 11:32 am

Your really not saving that much 10 grns of powder per shot. use it up and get the right powder would seem the better thing to do. I can imagine the pressure spike would be quite large with such a fast burning powder.
sungazer
Sergeant Major
Sergeant Major
 
Posts: 1525
Other

Re: Why is my pump over-pressuring?

Post by bladeracer » 27 Feb 2018, 12:00 pm

Oldbloke wrote:Remington pump 7615 might be rear locking?
If so that would explain it.



While I don't disagree, I do wonder why a rear-locking bolt would relate to increased pressure in the chamber.
My Remington 788 was a rear-locking bolt and while very hot loads did cause excessive case stretching I never saw any pressure signs.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 12655
Victoria

Re: Why is my pump over-pressuring?

Post by Oldbloke » 27 Feb 2018, 2:40 pm

bladeracer wrote:
Oldbloke wrote:Remington pump 7615 might be rear locking?
If so that would explain it.



While I don't disagree, I do wonder why a rear-locking bolt would relate to increased pressure in the chamber.
My Remington 788 was a rear-locking bolt and while very hot loads did cause excessive case stretching I never saw any pressure signs.


Perhaps some are better than others.
The greatest invention in the history of man is beer.
https://youtu.be/2v3QrUvYj-Y
Member. SFFP, Shooters Union.
SSAA, the powerful gun lobby. :lol: :lol: :lol: :lol:
Hunt safe.
User avatar
Oldbloke
Field Marshal
Field Marshal
 
Posts: 11192
Victoria

Re: Why is my pump over-pressuring?

Post by bladeracer » 27 Feb 2018, 2:58 pm

Oldbloke wrote:
bladeracer wrote:
Oldbloke wrote:Remington pump 7615 might be rear locking?
If so that would explain it.



While I don't disagree, I do wonder why a rear-locking bolt would relate to increased pressure in the chamber.
My Remington 788 was a rear-locking bolt and while very hot loads did cause excessive case stretching I never saw any pressure signs.


Perhaps some are better than others.


That does nothing to explain how chamber pressure can be increased due to a rear-locking action. If it causes the case to stretch excessively it could be argued that would cause less pressure due to increased volume.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 12655
Victoria

Re: Why is my pump over-pressuring?

Post by pcinvic » 27 Feb 2018, 3:04 pm

Hi Medic,
This is my first post on this forum but here is my 2 cents worth (been reloading for over 50 years all the way from 22 Hornet to 55 cal Boys anti tank). Your initial load of AP100 in your bolt gun seems to me to be "hot" for this powder but nonetheless did not take your gun apart, but it might be close to it. Consider this; AP100 was not designed to to operate at pressures that some rifle powders operate at and may be close to "going nuts" pressure wise. Here is a case in point; years ago I built a 450 Ackley on a Ruger #1 and wanted a lighter load for 500 gr hard cast bullets, 88 gr of #4064 was fine, 33 gr of Nobel #64 shot gun powder was fine BUT 34 gr of #64 resulted in case destroying pressures. This powder was NOT designed to be stable at higher rifle pressures and could become very unstable. Likewise AP100 although used in some reasonable pressure pistol rounds will very likely not tolerate higher pressures used in rifle ammo. As mentioned by others it is not a good idea to assume what works in one gun will work in another. I would suggest that you choose another more suitable powder; but even if you continue to use AP 100 in your bolt gun at least back it of 1 gr.
Cheers
pcinvic
Recruit
Recruit
 
Posts: 2
Victoria

Re: Why is my pump over-pressuring?

Post by Gwion » 27 Feb 2018, 3:06 pm

I personally think you're asking for trouble using pistol powder in a 223 and were probably just lucky there was no issue in your other rifle. Also, drpping the charge may have been enough to decrease you case fill enough to cause a flash over pressure spike or "Secondary Explosion".
User avatar
Gwion
Colonel
Colonel
 
Posts: 3978
-

Re: Why is my pump over-pressuring?

Post by Supaduke » 27 Feb 2018, 3:15 pm

The real question is why are you using pistol powder in a rifle? Regardless of results that strikes me as foolhardy. I guess 10 is too many fingers.
Supaduke
Warrant Officer C2
Warrant Officer C2
 
Posts: 1230
Victoria

Re: Why is my pump over-pressuring?

Post by Gwion » 27 Feb 2018, 3:25 pm

Supaduke wrote:The real question is why are you using pistol powder in a rifle? Regardless of results that strikes me as foolhardy. I guess 10 is too many fingers.


Yep. And two is too many eyes...
User avatar
Gwion
Colonel
Colonel
 
Posts: 3978
-

Re: Why is my pump over-pressuring?

Post by bladeracer » 27 Feb 2018, 3:28 pm

Agreed, makes zero sense to me to be using AP100 or AR2205 in the .223 with a rifle-length barrel.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 12655
Victoria

Re: Why is my pump over-pressuring?

Post by Medic » 27 Feb 2018, 3:48 pm

I’ve shot 2000 odd rounds with it in 3 different rifles so I think it’s pretty much safe. All bolt actions though. I just took it to a gunsmith to check headspace and all seems ok. But... it is a nato chamber not a 223. I asked if it could be reamed to 223 and he said he could but it’s some work.

When you do the maths 50% less powder load adds up. 2205 is even Less pressure and far more forgiving than AP100. I might go to that. 10 grains means every 3rd round is free compare to 2206H. Average velocity is 2980. Plenty.

One thing I will say is max I was getting was 2750 instead of 3000 which is significant with AP100. I think you guys might be right on the chamber just being different in geometry.
Medic
Private
Private
 
Posts: 74
Queensland

Re: Why is my pump over-pressuring?

Post by sungazer » 27 Feb 2018, 4:12 pm

You really dont ream a NATO chamber to a 223. The main differences are in the free bore to allow longer bullets and the headspace or distance from the case base to the shoulder datum is or could be longer. So to perform that he would need to add a few turns of thread to the barrel and cut it back commonly know as setting back the chamber. Many 223 chambers for target are sort of close to NATO without being sloppy in other areas so they can shoot the longer 80grn bullets.

It may be why you are not getting pressure problems as the bullet is able to get out of the case a fly some distance reducing pressure before it hits the lands is slowed and pressure builds up again.
sungazer
Sergeant Major
Sergeant Major
 
Posts: 1525
Other

Re: Why is my pump over-pressuring?

Post by Oldbloke » 27 Feb 2018, 5:36 pm

AP100 should be OK to use if the load is worked up. I use about 7.5 grains of AS50n to achieve hornet velocities in my 223.

Reduce the load by at least 10% or email ADI. They will help you.
Last edited by Oldbloke on 27 Feb 2018, 7:38 pm, edited 1 time in total.
The greatest invention in the history of man is beer.
https://youtu.be/2v3QrUvYj-Y
Member. SFFP, Shooters Union.
SSAA, the powerful gun lobby. :lol: :lol: :lol: :lol:
Hunt safe.
User avatar
Oldbloke
Field Marshal
Field Marshal
 
Posts: 11192
Victoria

Re: Why is my pump over-pressuring?

Post by bigpete » 27 Feb 2018, 6:13 pm

Usually has something to do with a seal. Try shaving your pubes and see if that helps
bigpete
Colonel
Colonel
 
Posts: 3577
South Australia

Re: Why is my pump over-pressuring?

Post by Gwion » 27 Feb 2018, 6:23 pm

bigpete wrote:Usually has something to do with a seal. Try shaving your pubes and see if that helps


Bwa hahahaha...
You shocka!
User avatar
Gwion
Colonel
Colonel
 
Posts: 3978
-

Re: Why is my pump over-pressuring?

Post by bigpete » 27 Feb 2018, 6:47 pm

Lol
bigpete
Colonel
Colonel
 
Posts: 3577
South Australia

Re: Why is my pump over-pressuring?

Post by Daddybang » 27 Feb 2018, 7:02 pm

bigpete wrote:Usually has something to do with a seal. Try shaving your pubes and see if that helps


Nice to know I wasn't the only one thinking along those lines! :lol: :drinks:
This hard living ain't as easy as it used to be!!!
Daddybang
Second Lieutenant
Second Lieutenant
 
Posts: 2012
Queensland

Re: Why is my pump over-pressuring?

Post by Medic » 17 Mar 2018, 3:54 am

So I did some more testing and some chronographing.

I’ve stepped away from the AP100 in favour of the 2205.
The average speed I’m getting out of a T3X with18.5 grains 2205 is about 3150 FPS with a 55 gr pill. You can go more but your gains drop off. No pressure signs at all.
With 20g 2205 and a 40 gr pill 3550. (ADI load data is pretty right) could push to 21.5 but no point.

Plenty good enough. The pump cycles fine with 2205 too.
I feel safe with to ap100 14 gr for a plinking load in bolt actions only 2900-2950 with 55gr pill. Will step that down to 13.5 for safety reasons for a nice dual purpose fun load. No good for pumpys though ;)
Just thought I’d update. Good fun.
Medic
Private
Private
 
Posts: 74
Queensland


Back to top
 
Return to Reloading ammunition