I've been working with a new Seekins SP10 in a 6.5 creedmoor. Last week I finally settled with my best load 142 SMK, 41.5 grains of H4350. The hornady eld-ex and 36.5 grains may have shot better but I wasn't happy with the velocity at about 2300fps. Anyways, my gun is beating the brass up pretty good and the seekins has an adjustable gas block which I believe is opened up all the way up. My question is will adjusting the gas block to my current load affect accuracy or performance. It's dialled in with this load and my ES is under 15 fps and SD is under 10. I'm just wondering if this is going to change the numbers and not make this load so consistent. If it does, I'll just deal with the brass problems.
Point of Impact/load performance affected by adjusting gas block?
- Thread starter giannid
- Start date
It "shouldn't". However, the only way you'll know for sure is to try it and see. Let us know. I'd be interested in your results for sure.
By dialing the gas back to the point you need to delay the bolt and hopefully keep it from beating the hell out of your brass you may see a small increase in velocity due to a longer dwell time.
I wouldn't expect a big boost in velocity but should give a smoother recoil impulse and be less wear and tear on your receiver components and brass.
Also curious if you are getting any false pressure indications such as swipes from your ejector plunger due to the bolt unlocking early from being overgassed ?
I wouldn't expect a big boost in velocity but should give a smoother recoil impulse and be less wear and tear on your receiver components and brass.
Also curious if you are getting any false pressure indications such as swipes from your ejector plunger due to the bolt unlocking early from being overgassed ?
The amount it would change velocity would probably be within your ES, i.e....a very small amount. Change it and see, you can always put it back where it was.
^^ what has been said.
at 100 yards, no change. At 1,000 yards, you will see some change. Hard to notice 0.1 MOA at 100 yards, but start to see it at 1,000. Also, what has been said, find you sweet spot, and dont change the gas volume.
at 100 yards, no change. At 1,000 yards, you will see some change. Hard to notice 0.1 MOA at 100 yards, but start to see it at 1,000. Also, what has been said, find you sweet spot, and dont change the gas volume.
I am getting some injector swipes on the brass but it’s not bad. The brass is taking a beating though. I usually don’t mind if the body gets a little nicked as it usually comes out in the fl die. The brass is getting whacked where it necks down which usually never comes out, not even with firing a few times. I put a piece of Velcro on the outside of the receiver where it bounces off to see if that helps.
My biggest concern with adjusting the gas block is that my final load is no longer the best performing one. From what you guys are telling me, that’s not the case. Next range trip I’m going to first dial the gas in then do my final sight it in. I’ll also run it through the chrono to make sure things have changed much. Want to make sure my velocity, Es and sd is close to what it was.
Another question, is it best to adjust the gas in cold weather or warm weather? I’m in Ohio and summer temps can be in the mid nineties and winter temps can be below zero. I just want to make sure I have enough gas for the gun to always cycle. I’m using h4350 which is supposed to be pretty stable.
My biggest concern with adjusting the gas block is that my final load is no longer the best performing one. From what you guys are telling me, that’s not the case. Next range trip I’m going to first dial the gas in then do my final sight it in. I’ll also run it through the chrono to make sure things have changed much. Want to make sure my velocity, Es and sd is close to what it was.
Another question, is it best to adjust the gas in cold weather or warm weather? I’m in Ohio and summer temps can be in the mid nineties and winter temps can be below zero. I just want to make sure I have enough gas for the gun to always cycle. I’m using h4350 which is supposed to be pretty stable.
This may be helpful. Part of the Gas block setup instructions from JP Rifles:
"Gas Block Setup
Most rifles cycle faster than necessary, and the resulting “bolt slamming” effect is a noticeable part of the recoil impulse. The main purpose of our adjustable gas block is to allow you to adjust the port pressure to the operating system, thereby fine-tuning the bolt velocity, which will result in a smoother shooting rifle especially if you already have a JP Recoil Eliminator or JP Compensator. Additionally, the JP Gas Block is also useful in obtaining optimum port pressure on otherwise difficult to run setups such as suppressed weapons, short-barreled weapons, or unusual chamberings for nonstandard cartridges.
To adjust for your load, turn the gas adjustment screw in all the way to close it off. Then, back it out approximately two full turns, and load one round in the magazine and fire. If the bolt holds open, the gas block is set. If the bolt does not stay open,it is short-stroking, and the valve should be opened about another half turn. Continue backing the gas adjustment screw out until the bolt holds open consistently on last round. Test this again with one round in the magazine.
Remember, if you change ammo, the rifle may not cycle reliably and should be tested again with any ammunition that you intend to use in actual competition. If you must use untried ammo, back out the valve several turns to ensure full cycling. You may want to Loctite the valve screw. It is also possible to shut the valve completely if you want to cycle the rifle manually for any reason. "
I've applied these setup methods to my JP gas block as well as other mfg's and it's worked well for me. I think it's best to work up your load, then set up your gas block.
"Gas Block Setup
Most rifles cycle faster than necessary, and the resulting “bolt slamming” effect is a noticeable part of the recoil impulse. The main purpose of our adjustable gas block is to allow you to adjust the port pressure to the operating system, thereby fine-tuning the bolt velocity, which will result in a smoother shooting rifle especially if you already have a JP Recoil Eliminator or JP Compensator. Additionally, the JP Gas Block is also useful in obtaining optimum port pressure on otherwise difficult to run setups such as suppressed weapons, short-barreled weapons, or unusual chamberings for nonstandard cartridges.
To adjust for your load, turn the gas adjustment screw in all the way to close it off. Then, back it out approximately two full turns, and load one round in the magazine and fire. If the bolt holds open, the gas block is set. If the bolt does not stay open,it is short-stroking, and the valve should be opened about another half turn. Continue backing the gas adjustment screw out until the bolt holds open consistently on last round. Test this again with one round in the magazine.
Remember, if you change ammo, the rifle may not cycle reliably and should be tested again with any ammunition that you intend to use in actual competition. If you must use untried ammo, back out the valve several turns to ensure full cycling. You may want to Loctite the valve screw. It is also possible to shut the valve completely if you want to cycle the rifle manually for any reason. "
I've applied these setup methods to my JP gas block as well as other mfg's and it's worked well for me. I think it's best to work up your load, then set up your gas block.
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