6.5 GAP 4S Pressure Issues

[jraulsten]

I have an issue with a gun that I have never seen in all my years of shooting and I'm hoping someone out there can shed some light on what is happening!

Recently had a custom 6.5 GAP built with Brux 1:8 barrel and Surgeon action. This gun is a tack driver, but every time I clean the gun my first few shots from a cold bore show signs of excessive pressure (pronounced ejector marks and slightly flattened primers). This happens even with a mild load (58.8 grains H1000). After 3-4 shots pressure signs disappear and I can shoot up to 61 grains with no ejector mark. I still get slightly flattened primers but that may be due to a relatively soft primer? I'm currently loading H1000 with Hornady brass, 215M primers and Berger 140 Elite Hunters. I at first thought I had left something in the bore from cleaning such as lint off a patch or not thoroughly removing all cleaning agents but I am very anal with my cleaning regimen. I bore scope the barrel each time to ensure everything is free of obstruction but the problem persists, even after 200 rounds through the barrel. I am totally frustrated......Is fouling resolving the issue? I can let the barrel cool to ambient temperature and have no problems as long as the barrel is not clean. I'm about to give up and shoot a slow load of 58.8. This mild load shoots in the .2s pretty consistently and only shows a light ejector mark the first few rounds. I started with 59.5 the other day and the bolt was sticky and I had very pronounced ejector marks you can catch a nail on. Again, there were no problems after the first few shots. I don't know whether to just settle for a slow 6.5 GAP or never clean the **** thing again!

I sincerely appreciate any help I can get on the subject. Trim length of the brass is fine, etc., etc. I have run out of things to look for....

 

[Predator 22]

Have you tried cleaning the chamber with something like breakleen after your normal routine?

 

[Georgiashooter]

Like predator 22 said, try taking a shotgun mop soaked with brake cleaner and clean chamber if you're not. Sounds like you may be leaving a light coat of oil/solvent in chamber

 

[WeiserBucks]

I can't explain the pressure after cleaning, but how often are you cleaning? Almost all high quality barrels will go a long time before cleaning is necessary. I personally don't clean until accuracy starts to degrade or if the rifle is put up for long term storage. There's a ton of old mans tales about cleaning, most are simply not true.

 

[Nickb1075]

Try not getting it super clean every time. I don't think it is necessary. I have shot rifles upwards of 3 to 400 rounds with no major cleaning, just a few wet patches let it sit and punch it out with a few dry patches. Sometimes I hit the chamber and throat with a nylon brush but that is very seldom. When the accuracy is not there thats when i do a good cleaning and get the borescope out. I have run into issues similar to yours but not as dramatic, after a thorough cleaning. Most barrels when spotless takes a few to settle down. Just my opinion.

Nick

 

[Nickb1075]

Also I was just thinking do you clean your barrel then store you rifle upright? A tiny bit of oil or solvent might be settling in the chamber. Just thinking out loud.

Nick

 

[jraulsten]

Have you tried cleaning the chamber with something like breakleen after your normal routine?

I used to do that but recently purchased a Bore Tech action cleaner and started cleaning by their instructions. After cleaning the barrel I use some C4 on a chamber mop followed by a dry chamber mop. Then I use C4 to clean the lug recesses followed by dry patches. I will certainly try your suggestion and let all know how it turns out. Maybe I'm leaving a light coating in the chamber???

 

[jraulsten]

I can't explain the pressure after cleaning, but how often are you cleaning? Almost all high quality barrels will go a long time before cleaning is necessary. I personally don't clean until accuracy starts to degrade or if the rifle is put up for long term storage. There's a ton of old mans tales about cleaning, most are simply not true.

I've been cleaning this one after every 50 rounds or so just because it's new (which is more than I typically do). I totally agree with you on the cleaning frequency though. My 6.5 Creedmoor with a Bartlein barrel only gets a few patches of Ballistol run through until 250 -300 rounds and I never have issues with pressure or accuracy.

 

[jraulsten]

Also I was just thinking do you clean your barrel then store you rifle upright? A tiny bit of oil or solvent might be settling in the chamber. Just thinking out loud.

Nick

Thanks, Nick. I am storing upright immediately after cleaning. Think I'll try the brake cleaner in the chamber and quit cleaning so often! The best load for the gun is 60.6 H1000 but I'm afraid to shoot it from a clean barrel......May not get the bolt open.

 

[5RWill]

There's something to note about leaving a the 6.5 SAUM dirty for a couple hundred rounds similar to a match rifle using nearly half the powder. Depending on what powder you use you could build up a carbon ring in the throat and spike pressure. Seen examples of this from Ledzep on the hide who cleans his every 100rds or so or he gets buildup. Also in the FB group. Especially shooting suppressed (which could be the culprit).

I'm not saying that's your issue, i don't think it is. I'd just monitor it before i ran 400-500rds down it without cleaning considering the amount of powder your burning. Truthfully i think it's stems from H1000 as it's sooty and filthy.

As to your original problem. Idk man. I would wipe down that chamber with a dry patch. Maybe even go so far as to take the barrel off so you can really get it clean.

Another question. Do you lube your bolt? If you lube you're bolt body really well and have rounds in the magazine it can pick up lube off the bolt body and that could be the cause. I'd clean everything down to it being completely dry. Take a Q-tip with CLP line the lug raceway and a dab of lug grease on the lugs so they don't bind, and go from there.

 

[Danny1788]

What speeds are you getting?

 

[jraulsten]

There's something to note about leaving a the 6.5 SAUM dirty for a couple hundred rounds similar to a match rifle using nearly half the powder. Depending on what powder you use you could build up a carbon ring in the throat and spike pressure. Seen examples of this from Ledzep on the hide who cleans his every 100rds or so or he gets buildup. Also in the FB group. Especially shooting suppressed (which could be the culprit).

I'm not saying that's your issue, i don't think it is. I'd just monitor it before i ran 400-500rds down it without cleaning considering the amount of powder your burning. Truthfully i think it's stems from H1000 as it's sooty and filthy.

As to your original problem. Idk man. I would wipe down that chamber with a dry patch. Maybe even go so far as to take the barrel off so you can really get it clean.

Another question. Do you lube your bolt? If you lube you're bolt body really well and have rounds in the magazine it can pick up lube off the bolt body and that could be the cause. I'd clean everything down to it being completely dry. Take a Q-tip with CLP line the lug raceway and a dab of lug grease on the lugs so they don't bind, and go from there.

I don't lube the bolt at all. I do agree with the cleaning. There is no way I could go as long as the Creed between cleanings. I start getting a carbon ring around the neck to throat area after 40-50 rounds. I can see where overly excessive cleaning may affect accuracy, but it shouldn't have an effect on pressure.

 

[jraulsten]

What speeds are you getting?

I get 3080 with 60.6 of H1000 and haven't checked the 58.8 load. I have not used my Magnetospeed for the first few shots of each sit, but I'm sure they are faster than the load would indicate.

 

[jraulsten]

Have you tried cleaning the chamber with something like breakleen after your normal routine?

Thanks! It worked!!